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PREPARE FOR PEACE -TIME COMPETITIONIn the more competitive days of peace, technical training will be a vital necessity to theEngineer who wishes to safeguard his position and make advancement. " ENGINEERINGOPPORTUNITIES " will show you how to secure this all-important technical trainingquickly and easily in your spare time. This 100 -page book is full of valuable informationand explains the simplest way of preparing for recognised Examinations. Among thecourses described are :

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THE B.I.E.T. IS THE LEADING INSTITUTE OF ITS KIND IN THE WORLD

193March, 1946 NEWNES PRACTICAL MECHANICS

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Inland - - - 10s. 6d. per annum.Abroad - - - 10s. per annum.Canada - - 10s. per annum.Editorial and Advertisement Offi:e " Practical

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'Phone : Temple Bar 4363Telegrams : Newnes, Rand, London.

Registered at the G.P.O. for transmission byCanadian Magazine Post.

Copyright in all drawings, photographs and articlespublished in " Practical Mechanics " is speciallyreserved throughout the countries signatory to theBerne Convention and the U.S.A. Reproductionsor imitations of any of these are therefore

expressly forbidden.

FAIR COMMENT

Owing

PRACTICALMECHANICSto the paper shortage "The Cyclist," "Practical Motorist," and "Home Movies" are

temporarily incorporated.

Editor : F. J. CAMM

VOL. XIII MARCH, 1946 No. 150

Science is News!SIR EDWARD APPLETON, secretary

of the Department of Scientific andIndustrial Research, stated during a

recent lecture that science is news to -dayas never before. Whilst I agree that sciencefacts, accurately presented, are news, thereis a great deal appearing in the daily Pressunder the guise of scientific news whichamounts to warping some trifling scientificfact; newly discovered by the reporter, butwell established in scientific circles, in orderto provide a flaming headline. In fact, it isone of the daily newspapers' failings thatthey are deserting their function of newsgathering and endeavouring to become dailymagazines. In this theysucceed against the specialist journals. Fewof them, indeed, take the trouble to employqualified scientific people to write scientificarticles. If science is news, there are somehundreds of scientific developments whichhave not been dealt with by the daily Press,merely [because they concern drab things,but are none the less highly important. Ifsome crank, however, invents a new mouse-trap, or a new seal for jam -jars, it attracts aheadline and a- half a column of type in ourleading newspapers. Of course, the facts arewarped to make extravagant claims for the" scientific development," in an effort to pepit up for the delectation of the more gulliblereaders of the. daily Press.

The too -early disclosure of a scientificdevelopment is, in my view, wrong. Itcreates a demand which cannot be satisfiedbecause ,the development is still in theembryo stage, and by the time it is readythe public have forgotten about it. Popularenthusiasms are apt to wane, and greatexpectations often lead to great disappoint-ments. Science is knowledge based uponaccurate observation of facts and their relationto general principles and known laws.The scientific method is the checking ofunbiased observations by reference to existingco-ordinated and experimentally verifiedknowledge.

Thus, the scientific method begins withobservation, advances into reflective thought,as a result of which a theory is evolved, andthis, in its turn, must be submitted to thetest of carefully devised and reproducibleexperiments before it is generally acceptedas true. This scientific method of approachis entirely English in its conception, and ithas been adopted throughout the world --in fact, it forms the basis of all scientificthought and laboratory experiments.

In the steel industry, the main heatconsumers are the open-hearth furnaceswhere the steel is made, and in order tosecure economies it was necessary to determinetheir heating efficiency. For this purpose it

was necessary to know, accurately, thespecific heat of the waste gases going up thechimney as well as their temperature, thespecific heat of the metal and of the slag overa large temperature range, including theliquid state and the heat value of the variousthermo-chemical reactions taking place inthe process of manufacturing the steel in thefurnace. It was found that only about25 per cent, of the heat supplied to the furnacewas being usefully employed ; 25 per cent.of the remainder was lost by radiation fromthe walls of the furnace and 5o per cent, waslost up the chimney. Boilers were, in somecases, heated by this waste gas, but they were

available waste heat.It was decided,' therefore, to instal better

designed equipment, and the result was thatthe recovery of heat was increased to 75 percent.

This, of course, does not interest the dailypapers, but it is a most important achievement,especially in these days of coal shortage.

Traditional KnowledgeTRADITIONAL knowledge, amassed and

handed down in course of time fromone generation tc another, can in certaincircumstances- be as exact as the knowledgegained by the scientific method. In fact,traditional knowledge still forms the basisupon which many of our older industries areconducted. In other words, it builds up asuccessful " know how." In an industrywelded, however, to traditional methods,new technical knowledge can only be acquiredsloWly, and so such an industry must beinflexible in its operations, and it is extremelydifficult for it to take advantage of any newmethods or materials. It remains stagnantand unprogressive.

We are living in an age where new materialscontinue to replace the old, and science hasdeveloped sufficiently for us to be able to saywhat particular qualities in a material weneed for a certain use. New materials andnew industries are not created by the wavingof a wand. They come by keeping watchon all contributory developments. Beforethe war, both uncreasable cotton and un-shrinkable wool had been produced in thiscountry as a result of prolonged research.During the war, cotton fabrics were producedin large quantities in which the fibres are sotwisted that on contact with water they swellso that the cloth becomes immediatelywaterproof, but still allows the passage ofair. Between the wars, England gained allthe speed records in the air, on water, andon land, and we hold all those records again.

We are apt to forget that perspex, thetransparent, non -splintering plastic, indis-

BY THE EDITOR

pensable for aircraft construction, was anEnglish invention, while another waspolythene, an essential insulating materialfor high -frequency cables, without whichRadar would have been impossible.

While much can be done immediately bythe application in industry of existing scientificknowledge, by way . of improving processes,reducing waste and generally in solving theday-to-day problems of production, sustainedfuture progress must depend on the applicationof new knowledge,which is being now obtainedin the laboratories as the result of fundamentalor pure research.

In Government or industrial researchorganisations such research shouldin its character. By this I mean that it shouldconsist of a long range attack on the basicgeneric problems that fall in the particularfield of the organisation. Usually objectiveresearch of this type is not intended to aimat immediate7practical results, but to gaining" physical " insight into some basicphenomenon such as corrosion, the oxidationof fats, or the growth of large molecules whichform plastics and proteins. Experience hasshown, however, that a basic attack of thiskind is often the shortest and most fruitfulroad to the solution of problems of practicalimportance.

Academic ResearchBESIDES such objective fundamental

research there is also the need foracademic research. Such work is not academicin the sense that it deals with " pure " scienceas opposed to " applied." It may involveeither or both. Obviously the best conditionsfor this type of work are those which prevailat universities or similar institutions. Itsencouragement is of the greatest importanceto -day, as research of this type has been inabeyance in many fields during the war, sothat there are nearly six years of progress tobe made up.

We must also look to the universities andthe technical colleges for the supply ofhighly trained research workers, upon whichthe future progress of all kinds of industrialresearch depends.

General Government support for universitiesis the responsibility of the University GrantsCommittee, but the D.S.I.R. makes specialgrants to individual workers to enable themto employ research assistance or to obtainspecial pieces of apparatus. The Departmentalso operates a scheme for training youngpost -graduate students in the methods ofresearch. Several large industrial organisationsare also making very substantial contributionsto universities ; for example, I.C.I. haverecently given 8o research fellowships, towhich no restrictive conditions are attached.


An Adjustable DrawinktableConstructional Details of a Useful Appliance

for the Draughtsman or MechanicBy F. HOOK

ADRAWING -TABLE is a most usefularticle for the practical meehanic topossess if he has to prepare drawings

or tracings. This article describes suchan accessory which embodies a simple featurewhich will enable the drawing board to belet down to a horizontal position, when itmay serve as a light work table. The table isdesigned to be large enough to take a sheetof 3oin. by 22in. (imperial) size drawingpaper, and to leave sufficient margin ofboard for pinning on notes and sketches.

The timber shortage need not deter anintending constructor as the easel may beconstructed from battens available fromshops which market wood for the home con-structor. In passing, it is interesting to notethat the table illustrated here, Figs. t and 2,was made entirely from some lengths ofsecondhand floorboards. Some care wasneeded to stop the holes with plastic wood.The framework may be painted or stainedand varnished, but it is advisable to leavethe surface of the drawing -board " in thewhite."

MaterialsMaterials needed may be listed as follows

(all measurements being finished sizes) :4 pieces for end cross -frames. 4oin. x 2lin.

6 pieces for crossbraces. 48in. x gin.2 pieces for stays holding cross -frames.

3oin. x 'lin.2 pieces for ends of stays. 2in. ;< ifin. x2 pieces for stays adjusting height of

table. 3oin. x I jin. x in.2 packing blocks at hinges. sin. x 2lin. x

Win.6 pieces for drawing -board. 42in. x 6in.

X tin.2 pieces for bracing drawing -board.

3oin. x 2in. x tin.

piece for bottomledge of board.48in. x 2in. x Win.

2 Sin. x lin. bolts,wing nuts andwashers.

4 2in. x lin. bolts,wing nuts andwashers.

3 tin. x lin. bolts,wing nuts andwashers.

6 'lit -1.x6. iro ncountersunkscrews to secureledge.

6 tin. 6 iron coun-tersunk screws forblocks at hinges.

24 Iin.x4 ironcountersunkscrews to securecross bracingframe to endframes.

ConstructionalDetailsThe first step in

construction is to planeup the timber for theunder -frame. Construct the outer frameshown in Fig. 3. The cross-bracings usedto give rigidity are screwed to the uprightswith tin. x 4 iron countersunk screws. Thetwo Sin. long blocks at the top are screwedand glued to the top of the side uprights inorder to build up enough width for the

in. back -flap hinges.Secondly, the inner frame is made to fit

inside the previous frame, Fig. 4. Only onepair of cross -pieces are used on this frame,as if a lower pair were used they would be

2*Packing pieces to

make up width of back flaphinges

38_

Fig. 3.-Details of the framework.

Ws.

lK

4c

Fig. L-Front view of the completed drawing -table.

inconveniently situated for the draughtsman'slegs when seated at the table.

The angles on the top and bottom of thefour uprights are approximately 5o deg. Thesemay be adjusted when the two frames arebolted together with 2in. by /in. bolts andnuts.

Drill the side pieces for the cross -staybolt holes (Fig. 5). At one end of each stay isa packing piece tin. thick, used to make thestay lie parallel to the general construction(Fig. 6). When these stays are bolted on, the

,..p., / ' /1 \ ))A M 7' IT -Ft 1 , . , . 1 , I

III 111111111111,1111

Fig. 8 -Method of slot -screwing.

whole assembly should stand quite rigidlyon the floor.

The Drawing -hoard TopThe construction of the drawing -board

can be taken in hand next. The essentialfeature of this part is that the top surfaceshould be smooth and " out of winding."The left-hand edge, along which the T-squaremoves, should be dead straight.

There are several methods of making up aboard of this width and the main probleminvolved is to make allowance for the con-traction (or expansion) of the board.

The five pieces of wood may be glued andjoined in several ways (Fig. 7), e.g. :

(a) A rubbed glued joint ;(b) A dowelled glued joint ;(c) A tongued and grooved joint.(d) Each board grooved and a common

tongue of plywood used.

March, 1946

JointingIn jointing up these five pieces it is neces-

sary to use a pair of 3ft. sash cramps. Theboards should be jointed in two pairs first ofall. When dry these two should be jointedwith the remaining piece.

When the assembly is dry, both sidesare trued up with a plane. The edges aretrued up also and the ends sawn square andsmoothed by a finely -set smoothing plane.

The end pieces to the drawing -board maybe dowelled and glued, allowing two dowelsper board. The disadvantage of this methodis that if the board contracts, it is liable tosplit or warp. Consequently, the method of

slot screwing " is to be strongly recom-mended. The batten is either screwed to theend of the board (Fig. 8) or across the backof the board (Fig. 9). The latter method iseasier.

In the first method lines are squared acrossthe batten and the ends of the jointed boardsto mark the position of the screws. Iron cisscrews (2in. Y 8) are screwed into the ends ofthe drawing -board on these lines, leaving

in. of the screws' length protruding. Inthe batten holes are drilled gin. diameter xdeep to take the heads of these screws. Aslot is now cut to each of these holes in.long x 7/32in. wide (i.e., wide enough toaccommodate the shank of the screw) asindicated in Fig. 8.

No glue is used in the assembly of thisjoint. The batten is placed over the screwheads and held firmly in place, whilst the end -(towards which the slots point) is struckwith a mallet so that the heads will be forcedinto the wood about lin. to gin.

The method illustrated in Fig. 9 is even

NEWNES PRACTICAL MECHANICS

7

410 ut WM bolt

Fig. 4.-Front and side views of the standframework. (Note how the ends of the legs

are cut at an angle.)

361,Q

simpler. For each screw drill two 7/16in.holes at distances of in. Now countersinkthese holes to about gin. diameter (Fig. 9b).Then cut a slot 7'32in. wide with a tin.chisel to join up the two holes. Bevel thesides of the slots to join up with the counter-sinks.

The screws are put into the centre of the

r -

Fig.Fig. 9.-Method of screwing batten to the back of the drawing -board.

Fig. 2.-Rear view of drawing -table:

Wviong nuend boll

o

195

At*" 2 V2

slots and screwed down to the back of thedrawing -board so that the heads bed downnicely into the bevelled groove.

As the board expands or contracts thescrews will move in the slots so that theboard will remain entirely flat.

The drawing -board may now be hinged tothe under -frame. Back -flap hinges are used.If procurable, a pair of hinges which take apartare useful (Fig. to). By using these theboard may he removed rapidly from the under -

Ledge to prevent theslipp,ng off of

papers, arc

'Meta/ anglebracket screwedto drawl/7g board

/ 1V2 back flap hinge

WW/n5U-Ir arod 6001

Fig. 5.-Side elevation of the complete assembly.

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30'


Mewing board

/kwv-sjerN

Wearier

wing nut

Fig. 6.-Details of hinged corner and wingednuts and bolts.

frame by undoing the height adjusting staysand merely moving the board sideways.

Two angle brackets are needed on the backof the board from which swivel the slopeadjusting stays (Fig. II.)

Lamp BracketReaders will observe a lamp at the top of

the drawing -board in Figs. s and 2. Thiswas originally a hasty improvisation, which

A. A plain glued joint

Joint dowelled andglued.

C Tongued and grooved

D Grooved both edgeswith plywood tongue

;4.1,3*.beir

has since served so wellthat it has now beenmade a fixture.

The bracket consistsof three pieces of woodjointed by 2B.A. screwsand wing nuts andspring washers. Thetop strip has a battenholder mounted on it(Fig. 12). For alampshade an8in. loaf tin wasused, a tin. dia-meter hole beingcut in the end ofthe tin with a

/ 72

>-

Fig. 11.-Angle bracket.

centre bit so that the tin willfit on to the batten lampholder.This tin nicely accommodatesa 6o- or too -watt bulb. A5 amp. switch is fixed in aconvenient place on the loweststrip of the support. Thislowest strip is bolted to a blockof wood 4in. x tin. x sin.), screwed under-neath the drawing -board. With this simplecontrivance a good light may be obtained

Fig. ro.-Details of hinges for drawing -board.

Fig. 12. - Frontand side views oflamp bracket

assembly.

at any point across the width of the boardwithout glare to the eyes of the draughts-man.

A New and Monumental Work!NEWNES ENGINEER'S REFERENCE BOOK

Edited by F. J. CAMM. 1326 pages. Hundreds of Illustrations, 12 25. (43/- by post).A Concise List of Contents

Heat Treatment and PyrometryDrawing Office PracticePatents, Designs and Trade MarksPlastics and Powder MetallurgyGear Cutting and Screw CuttingCentre, Capstan and Turret Lathe PracticeWire Gauges and Wire DrawingMilling, Planing and ShapingGauge and Screw Thread MeasurementSoldering, Brazing and WeldingPress Tools and PressworkTubes : Manufacture and Calculations

Metal Cleaning and Metal PolishingWorkshop MathematicsProduction and Quality ControlCosting and Time and Motion StudyAeronautical EngineeringTools, Jigs and FixturesCompressed Air PracticeConveyors and CranesCoolants and Lubricants. Panel BeatingBoilers. HydraulicsInternal Combustion Engines. Radio FormulaWorkshop Practice. Tables, Etc., Etc.

The new Waterloo Bridge, over the Thames, the ceremonial opening of which was recentlyperformed by the Right Hon. Herbert Morrison, M.P.Fig. 7.-Four methods of jointing boards.


'

Autocycle Care andHow to Keep

HE autocycle, although an essentiallysimple machine, nevertheless requiresa certain amount of care and atten-

tion to ensure a trouble -free, pleasant -running machine.

Being in a distinct class of its own, theautocycle combines features which are com-mon to both the pedal and motor -cycle, andit is hoped that the following notes will beof value and assistance to owners of thesepopular machines.

Considerable power is often lost throughworn, unlubricated and incorrectly adjustedchains. To inspect a chain for wear, removesame from the machine and place on alevel surface. By alternately pulling andpushing on the ends, any excessive wear isimmediately shown by undue movementbetween the links. Slight movement is per-missible, but a chain that shows muchwear should be discarded, as if used in thiscondition will very soon ruin the sprockets.Likewise, if the sprockets are in a very badcondition, having broken or hooked teeth, itis wise to replace these, to save unnecessarystrain and wear on the chain.

LubricationCare and thoroughness in lubrication con-

tributes in no small measure to long chainlife and smoothness of running. Thorough-ness of lubrication entails the removal of thechains from the machine, and a preliminarywashing in paraffin to remove any dirt andgrit adhering to same. This is followed bya few minutes' immersion in molten motor -grease, preferably the graphited variety. Afterremoval, and allowing the surplus grease todrain away, they are refitted back on themachine, observing that the spring link isassembled correctly, that is, with the closedend facing the chain's direction of travel.

Adjustment of the chain is made by slack-ening the spindle nuts, and giving theadjusters the requisite number of turns. Inorder that the rear wheel is centralised cor-rectly, count the number of turns given oneach adjuster. They should both coincide.

As a chain usually wears uneven, a tightpoint will be found at one position of itsrun. All 'adjustments must be made fromthis point, allowing approximately tin. upand down movement in the secondary chain,and lin. movement in the pedalling -gearchain. The adjustment for the latter chainis usually made by means of a jockeysprocket. After adjustment has been satis-factorily made, securely tighten all nuts.

The procedure enumerated above shouldbe carried out every 2,000 miles. In betweenthese times, the chains should be regularlylubricated with engine oil slightly thinnedwith petrol before application.

Brake AdjustmentAs these machines are fitted with internal

expanding brakes, a few remarks concerningthese will not be amiss.

A brake that judders when applied mayusually be cured by rasping the leading edgeof the lining, as indicated in Fig. r.

If, after prolonged use, it becomes neces-sary to reline the brakes, the following pro-cedure should be followed. Remove the oldlinings by interposing a screw -driver betweenthem and the shoe face, and levering off.The rivets are next removed by cutting andpunching out. The replacement lining isthen placed on the shoe, and carefully riveted

Fig. 2.-Method ofrepairing a Bowden

cable.

A. The nipple onthe Bowden wireready for soldering.

Machines in

MaintenanceGood Running Order

By E. S. BROWN

into position with the rivets provided. Theserivets are either aluminium or copper. Itis not permissible to use rivets of metal otherthan that specified above, otherwise with thewear of the lining, contact will eventually bemade with the surface of the brake -drum,and scoring will be the inevitable result.

The rivets are burred over on the back ofthe shoe by supporting the head of eachrivet on a short length of rod previouslyheld in a vice, and tapping over with aball -hammer. As each rivet is applied, makeChamfered o

EdgeBrakeLinings

DirectionOf

Potation

Fig. r.-A method of curing brake judder byrasping the leading edge of brake shoe.

sure that the head is down snug in thecounter -sunk hole in the lining.

When the linings are satisfactorily fitted,the leading edge should be slightly cham-fered off, to prevent any subsequent occur-rence of fierceness ind judder.

Some machines are fitted with back-pedal-ling brakes. These brakes operate byexpanding a phosphor -bronze cone intocontact with the hub shell. These brakesare very reliable. The only attention nor-mally required is regular lubrication. Lackof proper and insufficient lubrication is verysoon indicated by the brake becoming fierceand erratic in action.

1 8

1

B. Nipple solderedin place.

BearingsThe wheel bearings are adjusted by turn-

ing the adjusting cone with the specialspanner provided, having, of course, pre-viously loosened the spindle nut adjacent toit. The adjustable cone is usually fitted onthe right-hand side of the machine whenviewed from the saddle.

Correct adjustment is obtained by tighten-ing the cone until it slightly binds whenthe wheel is rotated. It is then turned backa quarter of a turn, and the spindle nutsecurely retightened.

The hubs will, of course, require regularlubrication, this should be done at intervalsof zoo miles with a good make of cycle oil.A few drops is all that is required at anyone time, otherwise any surplus oil may findits way into the brake -drums, and maketheir operation ineffectual. Other partsrequiring the attention outlined above are

the bottom bracket and pedal bearings, steer-ing -head and the various Bowden wire con-trols.

The steering -head bearings may be testedfor adjustment by standing astride the frontwheel, firmly grasping the handle -bars andalternately pushing and pulling on same.Any lateral movement should be taken up bymeans of the adjuster provided. Should thehandle -bars turn erratically with either agrating or clicking noise, suspect either abroken ball -race, fractured ball, or a com-bination of bath. The only satisfactorycourse to adopt is to dismantle the bearingfor inspection and, if required, renew thedamaged parts.

The various controls, such as throttle,clutch, handbrake, etc., are actuated byBowden cable. Acute bends in these cablesshould at all times be avoided, otherwiseadditional strain will be placed on both theinner and outer cables, with the eventualfailure of same.Repairing Bowden Nipple

Should a nipple pull through, the follow-ing is the correct method of repairing same.Carefully clean both the cable and the insideof the nipple, and apply a non -corrosive fluxto both. Thread the nipple on to the cableand spread over the end of same to forma stop. Then, with a hot iron, run thesolder well into the nipple and into the stopmade at the end of the cable. With sucha repair it will be almost impossible for thenipple to again pull through.

A similar procedure is required to repaira broken petrol union. In this case, owingto the admixture of oil with the petrol, itwill be necessary to wash the parts verythoroughly in neat petrol to remove any traceof oil. Afterwards furbish the end of thepipe and the inside of the union with emerypaper and apply the flux. Well tin bothparts with the soldering -iron, and while thesolder is still fluid, bring the pipe and uniontogether, pushing the latter on the pipe asfar as it NN411 go. Apply the hot iron for afew seconds to complete the fusion and,after allowing to cool, remove any surplussolder with an old file. Do not forget to seethat the union nut is on the petrol -pipeprior to soldering.

Incidentally, should a petrol union breakwhile on the road, a temporary repair isalways possible by means of smearing soaparound the inside of the union, and after-wards pressing the petrol pipe into place.To prevent any subsequent movement be-tween the two parts, a small length of insu-lating tape is tightly wound around both.

1010 -Wheel AdjustmentShould it be suspected that one of the

wheels is buckled, a simple test may bemade for this by supporting the hand on aconvenient part of the machine and holdinga piece of chalk in close proximity to the rimof the wheel. By slowly turning the wheel,the chalk will mark those places that areout of truth. If the degree of error is verymarked it will, of course, be necessary tocorrect same. Remove the wheel from themachine, and then the outer cover and tubefrom same. The buckle should now benoted and on the side of the rim where itoccurs, the spokes should be slightly loosened,and on the opposite side slightly tightened.This will have the effect of drawing that partof the rim into conformity with the rest.

198 NEWNES PRACTICAL MECHANICS Mach, 1946

Replace the wheel on the machine andslowly turn, and observe the result. It is'very probable, however, that several adjust-ments of the spokes will have to be madebefore the results are considered satisfactory.

It is likely that several spoke heads will beprojecting. It will, of course, be necessaryto remove these with a file before refitting theinner tube and cover.

In the event of a spill, the pedalling -cranksare the most likely to suffer. With care theycan be satisfactorily straightened by placingthem in a copper -jawed vice and applyingsteady pressure with either a twisting wrenchor large adjustable spanner. With a badlybent crank it is advisable to heat the dam-aged part prior to straightening to avoidundue fatigue of the metal. The heating,however, is somewhat apt to spoil the subse-quent appearance, especially if the crank isplated, and will necessitate replating orenamelling.

When refitting the cranks, it is advisableto use new cotters, as the old ones may have .worn to such an extent that they projecttoo far through the crank boss and so pre-vent the crank from being fully tighteneden the spindle.

Power UnitThe power unit fitted to the autocycle is

extremely smooth running. Should any

undue vibration be experienced, it is verylikely that the bolts securing the engineto the frame have worked loose. It is aswell, therefore, to occasionally test thesebolts to make sure that they are quite tight.A useful tip to keep these and other boltssecure is to smear the thread with motorgasket cement before tightening.

Other vulnerable places for loose nuts arethe mudguard stays, and where the mud-guard is bolted to the machine. These partsof the machine are subject to much vibra-tion and tend to loosen.

It is a strange but true fact that manyriders pay very little attention to securingthe most comfortable riding position an theirmachines. They will continue riding themexactly as delivered by the makers, althoughonly a few minutes' work with a spanner_would make an unbelievable improvementto the riding qualities.

It is impossible to generalise on this sub-ject, as the owner will have to make adjust-ments to the relative positions of the saddleand handle -bars to suit his own individualrequirements. It should be noted, how-ever, that the saddle peak is not poised toohigh, otherwise there will be a tendency forthe rider to lean backwards.

The size of the tyres as fitted to auto -cycles is 26in. by zin. by On.. When re-placement becomes necessary, fit " Carrier

Oversize " if you can obtain them. Theyhave approximately 3o per cent. greater aircapacity than the standard size, and giveenhanced comfort and wearing qualities. Oneprecaution is necessary before fitting theselarger tyres, and that is to see that there issufficient clearance on the machine for them.The overall increase in size for the largercover is about in., and when verifying theclearance, this should be borne in mind.

Protecting Plated PartsAn excellent method of protecting the

plated parts of the machine, especiallywhere they are worn thin, is by applyingcelluloid collodion. If this cannot beobtained locally, it can be easily prepared bydissolving some scrap celluloid in equalproportions of acetone and amyl acetate.This will take about 24 hours, and duringthis time it should be occasionally stirred.The collodion, when ready for use, shouldhave a consistency similar to varnish.

The plated parts should be prepared forthe protective coating by being well cleaned.Where chromium plate has worn thin, it isusual for it to become spotted with rust.This can usually be removed by a brisk rub-bing with a damp cloth, and afterwardsallowing to dry. The collodion should beapplied as quickly as possible, in a fullcoat with a soft brush.

London's New AirportLayout and Constructional Details of Heathrow Aerodrome

THE reason for was the needof the Royal Air Force for an airfieldnear London capable of handling the

heaviest types of aircraft, especially in theclosing stages of the war in the Far East as itwas expected to develop. In the planning itwas taken into account that such an airfieldcould be subsequently developed for civilaviation as the main terminal airport forLondon.

On January 1st Heathrow was handed overto the Ministry of Civil Aviation by the AirMinistry. The claims of other airfields nearLondon were considered when the questionof a suitable site arose, but none wassatisfactory.

Heathrow is only 14 miles from the centreof London, it is outside the built-up area, andis capable of development without extensivedemolition of private property. It liesbetween the Bath Road and the Staines Road,two of the best approaches to London, and iswell served by train services, being only twomiles from the Waterloo -Staines section ofthe Southern Railway, and the same distancefrom Hounslow West Underground Station.

Three RunwaysThe selected area included about 120 acres

of ponds and disused gravel workings, and aportion of the main runway would have totraverse - these ponds. Special drainageproblems were presented, as the discharge ofhuge quantities of water would have to beregulated so as to avoid flooding the surround-ing land. These and many other problemswere successfully solved, and in April, 1944,plans were complete for a three -runwayairfield of lengths 9,000, 6,000 and 6,000ft.,together with a perimeter track 25,000ft. longconnecting the ends of the runways. Thewidth of the runway was 3ooft. and that of theperimeter track sooft. The runways aresited so as to be capable of extension to 15,000,9,000 and 9,000ft. respectively.

The main east -west runway of length9,000ft. is now complete. The second

runway extending from the north-west to thesouth-east is practically finished. The arrivaland departure apron, together with temporaryterminal buildings, is also complete. Theinstallation of apparatus and the completionof the third runway extending from the south-west to the north-east will proceed withoutdelay, and the airport will be ready toaccommodate regular passenger services inthe summer. It will be the main Londonairport for transoceanic traffic. The internaland European services will make use ofCroydon and Northolt, though eventuallysome of them also will be accommodated atHeathrow.

Accommodation for Largest AircraftThis three -runway aerodrome will in itself

give London a first-class airport, capable ofaccommodating the largest aircraft nowcontemplated ; but in due course it is plannedconsiderably to extend the area and increasethe number of runways. Detailed planscannot yet be announced becausc they arestill subject to revision, but a thorough studyof the neighbourhood has been made in orderto safeguard the land and avoid unnecessaryinterference with dwelling -houses and ancientbuildings. It is not anticipated that thenumber of persons who will be displaced fromtheir homes will be large, and there will be nodisplacement until five or six years, by whichtime the housing position will be much easier.

The contractors, George Wimpey andCompany, Ltd., Denham, Uxbridge, beganwork in May, 1944. Throughout the firstsummer and winter the main operationsconsisted of pumping out the ponds, and thisinvolved the disposal of too,000,000 gallonsof water, the removal of half -a -million cubicyards of silt, bulk excavation over the area ofthe first runway and its appropriate perimetertrack, the refilling of the ponds and making upto levels in preparation for the actual con-struction of the runway and perimeter track.Concurrently with this operation, it wasnecessary to construct the large drainage

scheme required for the collection and disposalof rain water from the concrete paving andinvolving the laying of some 13 miles of largeconcrete pipes.

During the first summer and winter a totalof two million tons of earth and gravel wasexcavated, 36,000ft. ducting forthe electric cables were laid, and 6o milesof wire laid through these ducts.

On the main runway, 9,000ft. long by 3ooft.wide, the concrete paving is 12in. thick. Thelaying of this mass concrete paving was begunin April, 1945, and the bulk of the work wascompleted in three -and -a -half months.

Concrete Mixing and SpreadingThe most modern mixing plant was

installed on a scale not previously provided inairport construction in this country.

The mixed concrete was placed on therunway and perimeter track by modernmechanical spreading and compacting equip-ment to provide the density of concrete andrequisite finished surface. Tests of the qualityand strength of samples of the concrete, takendaily, show an average strength of over3o per cent. above the very high strengthdemanded by the specification.

When the three runways arc completed,more than 1,114,003 square yards of tzin.thick concrete will have been laid.

The foregoing facts give a picture of thescale of operations and magnitude of quantitiesinvolved. The results have been possibleonly because of the high degree of mechan-isation developed on other constructionprojects during the war with the consequentlarge reduction in the numbers of heavynavvy labourers required. At no time hasthere been more than boo men in this categoryemployed at Heathrow, the general averagebeing about 400.

Two hundred lorries, 40 mechanicalexcavators, 5o bulldozers and tractor -drawnexcavators, besides many other items of plantof the most modern type, have been used inaddition to the elaborate concreting equipment.

Considering the magnitude of the engineer-ing problems and the existence of wartimerestrictions and control of labour and materials,all of which was complicated by flying -bombsand rockets, the successful completion of thiswork is a credit to British engineering skill.


Heathrow AerodromeThe Ministry of Civil Aviation recently tookover the administration of Heathrow, thedesignated airport fir London, which is beingbuilt between the Bath and Staines roads, near

Hounslow.Air Vice -Marshal Donald Bennett, who formedand led the R.A.F.'s famous Pathfinder Force,celebrated the transfer of Heathrow aerodromefrom military to civil control by taking off inthe Lancastrian air -liner " Star Light" on a

survey flight to South America.

The huge mixing machine making concrete forthe runways.

Building one of the largerunways with a continuously -

moving machine.

Another view of the travel-ling machine for making th

runways.

Part of the new airport,showing, in the background,the Star Light" beingloaded prior to leaving for

South America.

The Lancastrian " StarLight" taking off for thefirst flight from the new

airport.


A Camera EnlargerBase, Print Holder and Focusing Screen

By " HOBBYIST "(Concluded from page 183, February issue)

IN last month's issue the enlarger case,negative holder and opalising screenwere described in detail. To complete

the work, the base and adjustable printingeasel has to be made, all the necessarydetails appearing in this issue.

The base is really a " sleeve " for theprinting easel arm, the latter allowing theprinting easel to be extended to a distanceof 2ft. bins. The arm keeps the easel inalignment with the lens of the camera.

The base also serves to hold the cameratruly in position. As' you know, mostcameras are Itted with screw sockets atone end and side for connecting to a tripod.This feature is made to suit the enlarger,a screw being fitted to the front, top -end ofthe base so that the camera can be screwedupon it.

421"

to make a half -lapped joint. Glue andscrew the parts together, as suggested. Thecross piece, being an kin. thicker, projectskin. at the bottom.

It is being assumed, of course, that theextension arm has been tried in its sleevingto see that it fits in and out smoothly. Itis better to have it a trifle slack than a neatfit, since the wood might swell with damp-ness in the atmosphere, or through applyinga stain, thus becoming troublesome toadjust.

The Print HolderInstead of the usual plain easel on which

the printing paper is attached, the writerpreferred to use a holder resembling aprinting frame. As a result, one is confinedto a certain size of enlargement all the time,

unless extra holders are made andattached when occasion demandsthem.

Experiment showed that the small-est frame was one taking 4}in. bySin. printing paper, the largestframe being one taking loin. by 8in.printing papers. The " between"sizes of printing papers are 8' in. by62in. and 6-lin. by 4kin., holdersbeing made accordingly. The frameholders, of course, ensure a neat,white border all round the print.

The best size of holder for the

0

_

8oit HoleRecessedFor Nut iF-

3

-121"

I" Dla1-iole

writer's requirements was one taking

Fig.1i.-Base parts of the enlarger, withsectional end view.

Ease ConstructionTo make the base, cut out the top piece

from kin. wood. A 3/16in. hole is boredat one end for the camera socket screw, thisbeing a tin, long gutter bolt -or any flat -headed bolt of a similar nature which suitsthe socket threads. Countersink the bottomside of the base top bolt hole and insertthe bolt, then fix on the nut.

The nut, of course, must be flush withthe surface of the base top, so cut a neatrecess for it, as shown in Figs. 11 and 12.Incidentally, it is essential that the bolt isso fixed in the wood that when the camerais screwed upon its projection, the latter issufficient to allow the camera to be a firmfixture moon the base when facing the frontend, i.e., the easel end of the base.

Having glued and nailed the side stripsto the underside of the top base piece (these:strips must be absolutely parallel at the:centre for the extension arm), cut out the:8°"-bottom piece from kin, plywood and affixon the strips. The tin. diam. hole cut at'the end of this piece allows the socket screwbolt to be adjusted, or removed, if necessary.!

The Extension ArmThe extension arm is a piece of kin. -thick

wood 36ins. long by On. wide, the crosspiece being a piece of kin. -thick stuff 6kins.long by sin. wide. One end of the arm ishalf -checked, as shown in Fig. 13, then thecross piece checked similarly in the centre

half-plate printing papers.. The partsfor this size of frame holder aredetailed in Fig. 14. The front pieceis cut from kin. wood to make aninner aperture 64ins. by 41ins.

The back piece is cut from gin.plywood, the central waste piecebeing carefully cut out with thefretsaw. A hole, for the entry of

the fretsaw blade, is made at onecorner, but you should drill tiny holes at allfour corners to facilitate turning the bladeat these points.

Glue and nail the front piece upon theback piece, and see thatthe rebate is evenall round, for any inaccuracy here willalways show on the prints. The wasteremoved from the back piece is used as aflap, as shown in Fig. 15, it being hinged tothe framework.

Nut Fits Posh n Top

`plywoodBottom

Fig. 12.-Exploded constructional view of baseparts.

e

FacePiece ...-

FOrMingRebate

Back.Piece

fi 1111

4

Fig. 14.-Front and back parts of print -holderframe.

A Focusing ScreenPrior to hinging it in position, however, it

is necessary to carefully remove a ply ofwood from one side. A piece of thin, whiteticket card (or a blin. by printingpaper) is adhered on the wood in place ofthe ply removed. This makes a white focus-ing screen on which the enlarged imageis adjusted satisfactorily before inserting theprinting paper.

If you use a printing paper to make awhite screen surface, have the back show-ing, this being pure white. The sensitiveside of the paper would, in time, tend tobecome a yellowish hue owing to exposureto the light. An old, useless, clean printcould be used instead of a new, undevelopedone, including a piece of white cartridgepaper, if desired.

It ought to be explained here, for thebenefit of beginners, that most commercialenlargers are fitted with a swivel cap havingan orange -coloured glass which is broughtbefore the lens when focusing enlargedimages on the printing paper, the latterbeing insensitive to orange light. In thecase of the home-made enlarger, there is noorange glass fitment, so one must first focusthe image on a white background, after whichthe printing paper is put before the back-ground and the exposure made. Thismakes little difference to the enlargementsin fact, it is a safer method, since thorange cap can, at times, be accidentallytouched with the hand, or it might be a fit -

Fig. 13.-Details of the extension arm.


on -the -camera -lens type which could falloff, thereby spoiling the printing paperbefore the finest ,adjustment was made.

Attaching the Print HolderThe holder frame back can be attached

by means of a single butt hinge or twosmaller butt hinges, as shown. Moreover,

Fig. 15.-Constructional details of printholder, showing how it is hinged on the extension -

arm cross -piece.

you can, if desired, have a piece of plain,thin glass fitted in the frame so that " curl "in the printing papers (especially the largersizes) are flattened out when the back isclosed and snibbed. If a sheet of plain glassis used, see that it is free from scores andwhorls, as these will reproduce and have adisturbing effect on the print. Further, itwill be necessary to remove an additionalply from the hinged back to allow for thethickness of the glass.

The holder, when completed, is attachedto the cross piece of the extension arm bya single hinge, as shown in the constructionalview in Fig. 15. Have it hinged so that,when sitting upright, the back is flush withthe edge of the cross piece. To keep theholder from falling forward, attach a brasshook and eye, or a roundheaded screw couldbe used in place of the latter.

A Medium HolderA good, useful medium-sized holder is

one taking 61in. by 82in. prints. If this sizeof holder is fitted with a good piece of thinglass, quarter -plate, and half-plate, includingpostcard sizes of printing papers can be used.When using the smaller sizes, always make apoint of keeping them in the centre of theholder. This becomes a habit in time andkeeps you accurate. Naturally, thesesmaller prints will be without a whiteborder.

Up and Down AdjustmentsBecause the negative holder, nor the easel,

can be shifted upwards or downwards, thisshould not deter you from getting the

enlargements correctly upon the printingpaper. Practically all stand cameras possessan up and down adjustment for the lens.

Thus, by moving the lens upwards ordownwards, one is able to raise or lower theprojected image. This is, naturally, a limitto these movements, but it is surprisingwhat can be achieved on the home-madecamera enlarger. It is primitive, in a way,but it should serve its purpose. The varioussizes of printing papers which can be usedare shown in Fig. 16.

a.

Maximum Size

6

44

MinimumSize

47.

6;

o.

Fig. 16.-The minimum to maximum sizes ofprinting papers suitable for the enlarger, the

holder being made accordingly.

The Horseferry Road CitadelA Description of the Power Plant in One of London's Underground Miniature Cities

IN 1940, at the most critical stage of thewar for Britain, three undergroundbuildings were erected at strategic points

in London to house the country's executivesin emergency. The largest of these was onthe already excavated site of an old gasometerin Horseferry Road, and it became generallyknown as the Horseferry Road Citadel.

Construction, power plant, equipment andsupplies were such that under the worstwar conditions, including poison gas, theCitadel could be inhabitable for at least threeweeks by a maximum of about 2,000 persons.Water supply in an emergency was to be froma deep -bore artesian well through the founda-tions of the building ; and food supplies formany weeks were normally held in store ; sothat the only supply to come in from outsidewas air. Under all circumstances the air had topass through conditioners, but if a gaswarning came through a gas filter was broughtinto circuit at the bottom of the main airintake.

Because of the course of the war, thebuilding was never put to full-scale emergencyuse. But in view of the extraordinary varietyof services-amounting in miniature to thosefound in any large city, plus others of a specialwar nature-which had to be provided, thepower generation and engineering equipmentis of exceptional interest. The Citadel itselfhas been put to use in housing Governmentdepartments, and the power for its serviceshas, in general, been obtained direct from thelocal electricity supply undertaking. But onoccasions of Grid failure the Citadel's serviceshave been maintained with complete successby the diesel-engined plant intended to copewith war emergencies. And in view of thehigh peak loads at certain times each day,

and the national fuel situation, these diesel -engine sets have been brought into regularoperation during winter months for a fewhours each day.

Power PlantThe heart of the installation is four Petter

two-stroke Superscavenge oil engines set togive 375 b.h.p. at 500 r.p.m., and directcoupled to 25o kW. Brush alternators. Eachcomplete set is mounted on a solid concretefoundation. The four engine generator groupshad to be accommodated soft. undergroundwithin a space of approximately 35ft. long

General view of the four 25o kW. Petter engine generating sets at the Horseferry Read Citadel,The two Heenan and Froude coolers are in the background.


by zoft. wide, .but additional space wasavailable for the switchboard and coolers.

Some of the reasons leading to the choiceof the Petter make of engine were thefavourable ratio of the space occupied to thepower generated, and the low exhaust tem-perature, both of which factors were of morethan usual importance in this sub=surfaceinstallation. The engines are started bycompressed air stored in steel cylinders at apressure of 35o1b. per sq. in., and pumpedinto those cylinders by one or other of twosmall compressor sets, one driven by anelectric motor taking its current from theGrid, and the other driven by a small petrolengine and used only when Grid supply is notavailable.

The Petter engines are cooled by waterwhich has itself to be cooled, and this is donein two Heenan and Froude coolers, throughwhich the engine water is circulated andcooled by an air draught provided by twomotor -driven fans. The exhaust gases fromthe engines are passed through Burgesssilencers, which are very well lagged in order

L

Air-conditioningMost vital of all the services are the

ventilation and air-conditioning. Up to9o,000- too,000 cubic ft. of air a minute aredrawn into the building under maximumconditions, and this is enough for fourcomplete changes of air in an hour, plus theair needs of the engine and cooler equipment.All the air for the building is taken down acentral duct to the bottom of the structure,and then passes through filtering and condition-ing equipment before being led to the roomsand the services.

Two points are of particular importance.First, the elimination of all poisonous gas fromthe atmosphere in the event of a gas attack ;secondly, the maintenance throughout theyear and throughout each day and night of thecorrect temperature and degree of humidity.Experience has shown that 55 to 6o deg.of relative humidity in conjunction with anair temperature of 68 deg. F. gives the mostsatisfactory conditions to the inhabitants.These values are maintained within very close

Nine -panel switchboard ; at the extreme left is the hinged panel for the synchroscope then thefour generating -set panels ; and on the right the five feeder panels for the building.

to prevent heat being transmitted into theengine room and making temperature con-ditions there intolerable.

The electric generators and all the mainelectrical equipment was supplied by theBrush Electrical Engineering Co., Ltd. Thefour generating sets are designed to operatein parallel with each other and with theincoming bulk supply from the Grid. Theytake over the whole Citadel load within acouple of minutes of the Grid supply beingcut off, and there is a Chloride battery installedto maintain the essential services during thissmall time gap. The switchboard for theengine -generator groups has four panels whichline up with five feeder panels controllingdefinite sections of the building. All theengine speed control operations can be carriedout by the shift engineer from the switch-board.

Principal services maintained by thesePetter engine -generating groups when theGrid supply has been cut off are : lighting ;ventilation ; air-conditioning ; boilerauxiliaries ; artesian well ; sewage disposal ;'surface water pumps ; and kitchen cookingloads. With the building fully occupiedunder emergency conditions these loads areestimated to need at least three-quarters ofthe installed engine power.

limits, and are under constant observationby the superintendent.

The ventilation and air -washing plantinstalled by Young, Austen and Young, Ltd.,comprises in essence three washer andfiltration plants, supplemented by three175 h.p. CO, compressors by J. and D. Hall,

Ltd., for refrigeration and a multiplicityof fans belt -driven from electric motors.

The gas filters and gas fan motor come intooperation through a remotely -controlledelectrically -operated damper at the bottomof the building's main air intake ; this actionputs the air through the gas filter circuit andmakes the metal to metal contract needed toclose the electric circuit controlling the gasfan motor and to keep that motor runninguntil the damper is lifted.

Though vitally important in a waremergency the artesian well would makelittle call on the power generated by thePetter engines, its motor taking only 18 h.p.But there are two other pumping operationswhich are of almost equal importance. Firstis the sewage disposal plant, the clearing ofwhich is effected by Shone pneumaticautomatic ejectors supplied with compressedair at a pressure of zo to 3o1b. per sq. in.The sewage cleared from the two settling tanksis pumped off into the local sewers.

The Citadel is sunk in some of London'smarshiest ground ; and the seepage troublewhich formed one of the principal engineeringdifficulties in building the present Victoriastation, not far away, are ever present in thisbuilding. The foundations of the Citadelincorporate a double wall ; water leakingthrough the outer wall is picked up in thecavity 'between the two walls and pumped outinto the mains ; similar pumps deal with thewater coming from certain springs just outsidethe walls.

Hot-water SupplySteam to give the hot-water supply through-

out the building is supplied by two PaxmanEconomic boilers designed for a workingpressure of 8olb. per sq. in. These boilersare located well underground, on the samefloor level as the Petter oil engines, and arefired by coal. Abutting on to the same roomare the fuel oil storage tanks for the engine -generator groups, and holding a total of25,000 gallons.

The working of the complete generating,ventilating, conditioning and pumping plantsis under the direct observation of the shiftengineer in his office, by means of a com-prehensive system f visual and audiblewarning signals ; and all the panels of theswitchboard are visible to him through thewindows and door of his office. Multi-purpose indicators are installed is the office,so that without leaving his desk the shiftengineer can check the air temperature,outside ; the temperatures in the incoming.air duct, after the washing process, and of thewater in the condenser sprays. Finally,there is a gauge to indicate that the ventilatingplant is maintaining that slight pressureabove atmospheric necessary to ensure thatno gas leakage into the building can occur.

FOR ENGINEERS -

Screw Thread Tables, SI-, by post 513.Refresher Course in Mathematics, 816,

by post 91-.Gears and Gear Cutting, 61-, by post 616.Workshop Calculations, Tables and

Formulae, 61-, by post 616.Engineer's Manual, 1016, by post Ill-.Practical Mechanics' Handbook, 1216, by

post 131-.Engineer's Pocket Book, 1016, by post

Wire and Wire Gauges (Vest PocketBook), 316, by post 319.

Dictionary of Metals and Alloys, 1016,by post III-.

Plant Engineer's Pocket Book, 61-, bypost 616.

Screw Thread Manual, 61-, by post 616.

Newnes Plastics Manual, 17/6, by post181-.

Newnes Engineer's Reference Book,42/-, by post, 43/-.

Published byGEORGE NEWNES, LTD., TOWER HOU3E,SOUTHAMPTON STREET, STRAND, W.C.


Modern Coal-mininA Machinery 2Cutting Chains, Gummers and Special Adapters

By G. F. HAMBLETON and S. McCALLUM

(Continued from page 132, January issue)

THE cutting chain is the next part of themachine to be considered. Thisconsists of hardened steel links and

boxes with a pitch ofEach box is slotted to carry a pick, which

is held in place by a set screw, four or fivetypes of boxes being used with differentangles of pick slots, so that the chain canbe built with a number of lines of pickpoints to give the best cutting result.

The chain runs round the jib, which isnormally 4ft. 6in. to 6ft. in length. It con-sists of a high carbon steel frame to whichare riveted top and bottom plates to keepthe chain on its course.

The jib is carried by a support bar clampedto the jib -head, which can rotate through adistance of more than 18o deg. round thegear -head frame. The chain is tensionedby an adjusting screw inside the jib andworking on a nut in the support bar. Whereconditions are suitable, the jib can be fittedwith a sprocket on the outer end to reducefrictional resistances.

The thickness of the cut is generally from6in. to 9in., although special thin kerf jibsand chains can be fitted which reduce thecut to 4in.Operation

The machine is set with the jib in positionready to start moving into the coal face. Thechain is then engaged and the jib is pulledround by the slewing chain which is hookedto the jib -head, and is drawn in by thehaulage rope working at its lowest feed.

When the jib is fully under the cut, andat right angles to the machine, a spring -loaded locking pin drops in position in thejib -head. The feed is then transferred tothe drum nearest the face, the end of therope being first run out and held in positionby a prop.

The cut is then continued along the face.Up to a few years ago the small holingsor gummings thrown out by the chain had

to be shovelled awayby a man working atthe gear -head end ofthe machine. Much ofthis was carried backunder the cut, andhad to be cleaned outto make shot firingefficient.Mechanical Gum-

mersThis work has been

eliminated in manycases by the develop-ment of mechanicalgummers.

There are varioustypes which removethe gummings in dif-ferent fashion, themost successful work-ing on the spiral wormprinciple. I n t h eSamson machine thegummer, which isclamped on to themachine in one min-ute, is driven by asmall bevel pinionengaging in the gear -head crown wheel,then through afurther bevel gear drivingeach side of the gear -box.

The removable gummer frame is clampedto this gear -box, and the drive from eitherside, depending on which way the machineis cutting, is taken up by a spring -loadedclutch through a train of straight -cut gearscarried on ball and roller bearirgs to thegummer worm shaft.

The worm runs in a cylindrical chamberwhich receives the holings thrown out bythe chain, the sniral then pushing the holings

through the end ofthe cylinder, leavingthem neatly piledalong the goaf side ofthe coal -cutter's path,ready for disposal.

A further advantage ,

is that it safeguardsthe man behind themachine from any riskof being caught in thechain or should therebe any chain breakage.

Cutting the face with an A.C. longwall Samson. The machine ishauled along by winding in the drum on thf face side, the end of therope being fixed by a prop. The face conveyor is shown in position ready

for commencement of the loading shift.

Side discharge gummer being fitted to machine at beginning of shift.The driving gearbox is seen bolted to the gearhead frame.

a clutch -shaft on

Over -cuttingBy turning the gear -

head upside down thecoal -cutter can beused for over -cuttingt3in. above floor level,and further heightscan be attained bypacking between thebase plate and themachine, or by fixing

distance neck be-tween the gear -headand jib -head and fit-ting a longer sprocketshaft. By using jack-ing gear worked onthe screw principle,

adjustment can be made in the eatingheight to enable the machine to cut its ownroof. The Samson machine can also beadapted for short -wall work. In thisapplication the jib is kept locked in a straightline with the body of the machine and isfed into the coal at one end of the face.When the jib is fully under the coal thecutter is pulled sideways across the face tocomplete the cut.

Arcwall WorkingTo fulfil these operations successfully the

drums are fitted on an extended drum shaftto give the ropes a clear way to the gear -head end, and a special jib -head fitted withpulley brackets is also required to allow fullscope with haulage rope. The flitting speedis also stepped up to 4oft. per minute to savetime in moving from one face to another.

The longwall arcwall Samson, as its nameimplies, can be adapted for either longwallor arcwall working. It is fitted with a longergear -head to take a jib -head that can beslewed round by the chain and haulage ropein one continuous sweep while cutting inan arc 240 deg. and up to loft. in radius.

When arcwalling, the machine is mountedon wheels or crawlers, the drive for samebeing taken from the large spur wheel onhaulage drum shaft, through a reversing gear,box bolted to the upperside of the haulageframe and hence by chain drive to the wheelsor crawlers.

Loading and ConveyingTurning to the handling of the coal, after the

cutting and shot firing process, speedierhandling is duly carried out by varioustypes of conveyors, e.g., shaker conveyers,belt conveyors, and loaders, some of thelatter actually loading on to the coal lac&conveyor itself.

The modern face conveyor consists of asectionalised structure carrying idler rollers

204 NEWNES PRACTICAL MECHANICS

,,,xtvgtezt.a.4:2Z1V0

Troughed belt conveyor with underneath drive.the side

for top and bottom belts, the bottom beltbeing protected from dirt and small coal byinverted troughs. This keeps the returnpulley clean, thus reducing friction and wearto a minimum.

The side plates of the structure preventsspillage.

The belt consists of a number of layersor piles of cotton duck impregnated withrubber and protected by a layer of rubberon both sides, and at the edges.

The cotton duck enables the belt to with-stand tension and the rubber prevents thecotton rubbing and cutting, and also reducesinternal friction by insulating the strandsof the fabric from one another.

The width of a face belt is usually fromt8in. to 26in. and the length is, maybe, upto 3ooyds

At the tail end the belt passes round apulley which is pulled out from the mainstructure by sylvesters chained to props,thus applying tension to the belt. Fineradjustment is made by a screw device appliedto the pulley frame at each side. The troughon the frame is connected to the rest of theconveyor by a telescopic trough which ensurescontinuous protection for the bottom belt.

Face ConveyorOn the M. and C. face conveyor, the

driving unit, which stands at the deliveryend, consists of two cast steel side cheekswhich are held together by cross stays. Apair of driving pulleys, one of which has ahollow shaft, are carried between the cheekson ball bearings.

On one side the motor is spigoted to thecheek, and spur gearing transmits the drivefrom the rotor shaft through a solid shaftinside the hollow shaft to the other side,where a further train of gears takes the driveto the pulley shafts.

When the power is compressed air, theunit fitted is usually a turbine working onthe same principle as the compressed -airSamson, the flow of air being automaticallycontrolled by a governor fitted to one rotorshaft, this keeping the belt running at auniform speed.

A reciprocating air engine can be fittedin place of the turbine, Holman Bros. unitbeing a typical example. This consists oftwo cylinders set at a V -angle to one another,the pistons of which both drive on to onecrank shaft. The belt is wound between thedriving pulleys and snub nulleys to give thenecessary amount of belt wrap. Deliveryis either into the receiving end of a scraperloader or gate belt conveyor, or straightinto tubs, and extended delivery head beingfitted if necessary.

The complete cycle for operations at theface, viz., cutting shot firing, loading, tim-bering and turning over face conveyor readyfor the next loading shift usually takes 24hours.

The main gate conveyor is a more permanentstructure than the face unit, and can belengthened by the addition of sections at thetail end as the face recedes from the mainhaulage road.

To increase the capacity without resortingto the side -plate the belt is formed into atrough shape. This is done by havinghorizontal idlers in the centre of the belt

Showing loop take-up. The belt is trozighed byidlers.

and side idlers carried on brackets at anangle to give the suitable depth of trough.The idlers and brackets are bolted on to thepressed steel inverted trough sections whichcover the return belt. The side idlers aregiven a slight tilt in the direction of travelto assist the belt to run centrally.

The driving gear may be placed at thedelivery end, receiving end or somewhere inbetween on the return belt, depending onprevailing conditions.

A receiving end structure is fitted to take thecoal from the face conveyor, and as it ismoved forward in conjunction with theface each day, it follows that the wholeconveyor has to be extended.

Loop Take -UpA loop take-up and telescopic trough

eliminate the fitting of extra belt and troughseach day.

The loop take-up has its maximum length

March, 1946

of belt in hand when the troughs are closed ;as the face advances the whole structure canbe extended by pulling the receiving end along,the telescopic troughs opening out while theextra belt length is taken from the loop andtensioned up again by the pulley and jackarrangement in the loop structure. The loopbelt length is in the region of 6oft. which isample for a week, more troughs and beltingbeing fined during the week -ends.

Sometimes two or more gate conveyorsdeliver to a trunk conveyor in which casea system of sequence control may be includedin the motor switchgear, so that when themain truck conveyor is stopped all othertributary conveyors automatically come to ahalt.

On restarting again the gate and faceconveyors follow up on the trunk conveyorat intervals of a few seconds, according tothe timing of the relays fitted on each individualswitch.

Other types of machine mining plantinclude scraper chain loaders, Joy loaders,duckbill loaders, shuttle cars and various typesof shortwall coal -cutters which, owing tolimitation of space, cannot be described atpresent, but they are mentioned to illustratethe variety of appliances which are used inmodern coal mining. Prior to the war a greatdeal of the mining machinery used in Europeand the Dominions was of British manu-facture, and there should be a tremendousfield for post-war trade to these and manyether countries.

An Electric 3eBy Prof. A. M. LOW

N these times of fuel and blanket difficul-ties-1 it is not always easy to keep warm

in bed. Hot-water bottles are often un-obtainable, and we have no time for thewarming of sheets with pans of hot coalas used by our great-grandfathers !

A 2 8 I

35

I. One Gallon Oil Tin Or SmallBiscuit Tin.

2. Side Cut Out From A -B.

3. Fins -Five Are AttachedTo 2 & Lift Out Together

4. Bulb

5. Bent Tin Support ForSocket Soldered To Tin

At C.Section At D -E

Sectional views of an electric bed -warmer.

Warm pads contain hot wire resistanceswhich are necessarily thin and repairs canmean weeks or months of delay. Anyonewith a few kitchen materials " or who iswilling to spend five shillings on the neces-sary parts can make a warmer which isunbelievably cheering on a cold night.

The sketch shows the method adopted.Bulbs waste about 97 per cent. of theirenergy in heat; and a 4o -watt type is usuallyample. If regulation is desired two can beused and a simple switch is easily fitted. Thevanes, or fins, must be carefully made so

-warmerthat the heat is conducted away, or the bulbswill not last.

The whole device is safe, simple, andbreakdowns are a rare occurrence. It canbe repaired in 3o seconds. Running cost ismerely the normal bulb consumption.

With a cover made from a piece of oldblanket, the apparatus is a blessing andwill be appreciated during the winter whencoal fires are somewhat " under the counter,"instead of in the grate!

ELECTRICALLY HEATED CLOTHINGTHE subject of an invention recently

submitted to the British Patent Officeis electrically heated clothing which formspart el, the equipment of airmen.

The author of this improved device remarksthat for connecting a heating clement to thesource of the electric current a plug andsocket arrangement would be most con-venient. But this has the disadvantage thatthe plug and socket are liable to be pulledapart by the movement of the airman or,as high altitudes, owing to contraction dueto low temperature.

In the case of the newly invented electric-ally heated clothing it has a plug and socketconnection whereby one member of a readilyreleasable two-part fastening device is con-nected to the plug and the other memberto the socket. The fastening is so arrangedthat an indissoluble union is effected.

For this purpose one member of thefastening device may be attached to the plugor socket and the .other to a band or strapwhich is attached to the socket or plug. Theband is of such a length that, when theIwo parts of the snap fastener are engaged,the plug and socket cannot be disconnected.

Obviously the source of the current is oflow voltage.


The Story of Radar 5Radio Navigation Altimeters : Fighter Direction : Airborne Radiolocation

(Continued from page i68, February issue.)

AN apparent inconsistency in the precedingarticle is explained by the fact thatCoastal Command got its first " radar "

navigational aid as an unplanned by-product.It will be clear that if an A.S.V. set can getradiolocation echoes from a ship or a U-boaton the surface of the sea, it will also getechoes from islands, headlands and the like.The range of pick-up varies with the sharpnesswith which the landmark rises from the sea,and with its size. In general a coastline willbe shown on A.S.V. at ranges much exceedingthose given by ships. So the A.S.V. set couldbe used for making landfall in bad visibility,and a crew working on a familiar coast orwith some experience in map -reading fromthe radiolocation standpoint could get veryvaluable guidance. This free service was sopopular that the scientists sometimes wonderedwhether A.S.V. was not carried mainly forgetting about rather than for its officialpurpose of finding enemy shipping.

A natural development from the fact thatthe range of the nearest echo from the groundor sea was that from vertically underneath,and therefore measured the instantaneousheight of the aircraft above ground, was tofly across country by the aid of the " terrainclearance indicator " thus available. An earlyexperimenter guided an aircraft, flying blindsave for his radiolocation information ofthis special kind, across country in severallong flights, including one which simulateda bombing attack on Carlisle after an indirectflight of several hundred miles.

In the same series of experiments it becameevident that some discrimination among thedifferent components of a landscape could bebased on the returned echoes; the cranes atHarwich, for example, were useful radiolandmarks. This kind of discrimination waslater exploited in the centimetric aids tobombing, described in the section " Findingthe Target."

It will be seen from the foregoing examplehow interlaced were the many early develop-ments of radiolocation ; a device was nosooner developed for one purpose than it wasfound to provide wholly or in part thesolution to some other problem, and a newline of development would be marked downas soon as effort could be spared for it.

But the altimeter is an essential flyinginstrument and for many years the onlyindication of " height " was the reading ofan aneroid barometer which had been " set "before take -off to the height above sea -levelof the aerodrome from which the flightstarted. Even if the weather conditions didnot change during the flight, the best thatcould be expected was that while over waterorland at sea level the aneroid would indicatetrue " clearance." The same reading would beobtained in level flight if, a few minutes later,the aircraft flew over mountain peaks to,000ft.high : with disastrous results if the flightaltitude were only 9,000ft.

This is not a fanciful possibility-only toooften have aircraft flown into mountain -sidesin weather so " thick " that disaster wasupon them before the pilot could take evasiveaction.

What was needed, clearly, was an instru-ment to show " terrain clearance," the truedistance from the aircraft to the nearest partof the earth's surface, so that if this clearancebecame dangerously small the pilot could gainheight and avoid danger.

A commercial organisation in U.S.A. hadproduced before the war a device in which

How radar helped the Dover coastal artillery to sink enemy ships on the darkest nights. Ourillustration shows the interior of the coastal artillery operations room, situated in the dungeonsof Dover Castle. Here all the radar information was co-ordinated and the heavy and mediumcoastal guns directed on the enemy. On the right is seen Brigadier C. W. Raw, O.B.E., T.D.,

who was in charge of the radar operations at Dover Castle.

continuous electric waves were emitted, withrhythmic variations in frequency, from theunderside of the aircraft. The reflected wavefrom the earth's surface is received in theaircraft and " compared " electrically withthe wave then being sent out. The longer thetime interval between the emission of theoriginal wave and its reflection back to theaircraft, the more will its frequency differfrom that of the wave being emitted when itgets back. This frequency difference wasmade to show true " terrain clearance "directly on an instrument dial and for smalland moderate distances-e.g. up to 5,000ft.-the system works well.

Terrain clearance may involve also themeasurement of clearance obliquely ahead(as in approach to, or flying through, steeplymountainous country). In such cases, theindications can be combined, for peacetimeuse particularly, with a warning that otheraircraft are in the vicinity and the apparatustakes on the general character of A.I., alreadydescribed, but it has not been found necessaryto use such equipment in war.

The Story of Fighter DirectionThe growth of the coastal chain of Air

Ministry Stations which was the first andmost urgent application of radiolocation hasjust been described as if it had been designedas a purely passive information service.Indeed, had it done no more than give theAir Raid Warnings which it supplied forA.R.P., it would have amply repaid the fewtens of millions of pounds which it cost. Theelimination of standing patrols from thefighter defence of Great Britain, the eliminationof permanent " action stations " from theanti-aircraft gun defences, were in themselvesrevolutionary economies. Of the former theAir Ministry said in the first instalment ofthe story of radiolocation (June, 1941) :" Although millions of pounds have been

spent on Radiolocators it is safe to say thatthe entire cost has already been saved.Radiolocation makes it largely unnecessaryto maintain standing patrols and so it hassaved the country an immense expenditure onpetrol, engines and wear and tear of aircraft.It has also obviated the tremendous strain onpersonnel which, otherwise, would have beenunavoidable. In the Battle of Britain, theadvantages of Radiolocation were even moreapparent. Our sorely overworked fightershad no need to maintain standing patrols.They could rely on the vast Radiolocatorsystem to tell them in plenty of time whenthe enemy were coming and from whatdirection. This was of such incalculable helpto them that independent observers from theDominions have stated categorically that theBattle of Britain was won by the FighterOrganisation of the Royal Air Force aided byRadiolocation."

No such narrow limits to their ambitionsas mere passivity were set by the pioneers ofradiolocation. In particular, the chairmanof the scientific Air Defence Committeeseized enthusiastically on the possibility ofgiving to the fighter pilot in the air an accuratestream of information as to the position of theenemy relative to himself and of instructionson the course which he should fly to comewithin visual range of them, and to comewithin thato range in a relative positionfavourable to himself in engaging combat.Long before radiolocation equipment wasready to give actual information of this kind,experiments had been started on controlledinterception at the Biggin Hill fighter station.There a scientific study was made of the mostsuitable method for controlling interceptingfighters, making use of the communicationequipment at that time available. Duringthese trials at Biggin Hill it was assumed thatthe results from Bawdsey would eventuallybe such that the position of an aircraft would


be correctly determined once every minute With the confidence borne of past successand that the information could include and present ignorance the experimenters saidplan -position and height. By December, they would do R.D.F.II, but the sweat and1937, both the location and interception tears required were not at all proportionatetechnique had been evolved to a sufficient to the smaller size of the equipment or thedegree for a programme of interception smaller range required ! The proposedexperiments to be initiated, and from the solution was amplified to the Air Defence1st January, 1938, to the opening of the Committee at a meeting on February znd,present war, a very large percentage of civil 1936 ; the promise was then made that sixair liners reaching this country were inter- months' work on the ground would sufficecepted by fighters based at Biggin Hill and as a foundation for flight trials in a lightcontrolled from the Biggin Hill Operations bomber, and it was at the same time forecastRoom ; although in order not to excite too that centimetric wavelengths would later begreat an interest on the part of their officers, required for a fully satisfactory solution.the air liners were never " closed " by the In September of 1936 the " airborne " groupintercepting fighters. During these experi- consisted of three members and in spite ofmerits, a visitor to Biggin Hill was duly many diversions to give urgently -needed helpimpressed by the navigational paraphernalia in other fields these three experimenters setused to calculate what direction should be out to devise an equipment, light enough,given to fighter aircraft. One day, the R.A.F. small enough and taking sufficiently littleOfficer Commanding came into

. .

the Operations Room, mountedthe control dais and watchedthe process for some time,after which he casuallyannounced that he was quitecertain he could do just aswell by estimating whatinstructions to give to thefighters instead of makingthe calculations that werethen being worked out. Heaccordingly instructed that theOperations Room tableshould be cleared of all butplotters and took charge. Hisefforts met with suchremarkable success that it isnot an exaggeration to saythat this incident was the birthof the Day Fighter Controlsystem which was universallyemployed by the R.A.F.through the Battle of Britain.

By the time the war startedwe pl otted cross -channelaircraft so regularly that aninvestigation was made intoevery individual case of civilair liners being missed by thesentinel stations.

Had these experiments notbeen begun before there wasa solid foundation on whichto establish them, had they not been pursuedwith skill and zeal by service officers andcivilian scientists in the closest co-operation,then the technical readiness of the coastalchain for the day Battle of Britain wouldalmost certainly have been stultified by theinability to attain -tactical readiness in theground and air organisation for controlledinterception by day.

The Beginning of Airborne RadiolocationThe problem of daylight interception is

only the easy part of controlled interception.In spite of the imperfections of the coastalstations it was not difficult to guide thefighter to within a very few miles of his prey.When the prey flies by night the guidance isneither worse nor better, but the pilot's rangeof useful vision is now restricted to a fewhundred yards-sometimes to a few hundredfeet. All this was clear to the early radio -location workers and the scientific ;in. DefenceCommittee. The problem before the smallgroup of " airborne radiolocation " experi-menters was to go on from R.D.F.I., thecoastal station project, to R.D.F.II, theformidable problem of putting a completeradiolocation equipment, transmitter, receiverand indicator, into a night fighter, so that thecrew could, from the position to which theground controller could direct them (a fewmiles from the night bomber) seek hifn outand close into visual range by the use of hisown radiolocation set-the " smeller," as Mr.Churchill called it.

A corner of an operations room, showing heavy anti-aircraftfire -control radar equipment. Many gunners and A.T.S.operators have spent long hours at these controls searching for

enemy bombers and directing the fire of A.A. guns.

power from the meagre aircraft generatorsthen available to go in a tighter aeroplane.

By mid -1937 the equipment was still verycrude, but was hopefully put in an Anson,the transmitting dipole being poked throughthe escape hatch, while the receiving aerialwas kept inside the aircraft. To the great joyof the experimenters, echoes from ships wereobserved at four or five miles. This was animportant development of which more later.

A year later, a flight of aircraft was allocatedto the airborne experimenters at Martlesham :two Ansons, a Harrow, and later two Battles,some of which were always unserviceable atany given time, but sufficient remained togive opportunities for remarkable experimentalprogress in successive flights.

In 1939 a period of great activity wasfollowed by so many simultaneously -ripeningfruits that it was embarrassing to select onefor immediate development at the expense ofthe others : the device of switching from oneaerial to another enabled " port and starboard,"" up and down " lobe -switching to giveprecise " direction -finding " in two dimensionsand the success of this method was anothermilestone and the basis of all early A.I. (andA.S.V.). Also, a rotating dipole and synchro-nised rotation of the " time base " of thecathode ray tube (as related in the chapter onC.H.L.) was the forerunner of many airbornedisplay systems at present in use.

Again, it was observed that ground echoesfrom " towns " were stronger than thosefrom the " countryside " and Norwich. was

detected at a distance of several miles, whilestill invisible to the pilot of the " Battle."Here was a first foreshadowing of that aid toprecise target location which has made theR.A.F. so devastating in its attacks onindustrial Germany.

During the winter of 1939 and the firsthalf of 1940 much concentrated hard workwas put into the development of A.I. Improve-ments were made in minimum and maximumranges and in the serviceability and reliabilityof the gear under flying conditions. It wasvery clear to the experimenters, although itis not obvious on a first casual glance, that the'problem of reducing the minimum range atwhich useful information could still beobtained was much harder than that ofextending the maximum range.

By summer 1940 A.I. Mark III wasbecoming operational in Blenheims with aminimum range improved to 800ft. and amaximum range of about two miles. Thesystem was, however, still incapable ofdefining with sufficient accuracy the directionin which the bomber lay relative to thefighter. This problem was very acute andadvantage was taken of every minute ofdaylight for flying experiments on it. TheFighter Interception Unit, which had beenformed to work out the tactical utilisation ofdevices of this kind, began trials in August,1940. The results were impressively promisingand A.I. Mark IV was approved for use in theBeaufighter which, with this great advantagein speed, was replacing the Blenheim as anight fighter.

In July and August of 1940 there wereseveral " chases " by A.I. fighters and thefirst claim-a " probable "-was made byF.I.U. on the night of znd-3rd July, 1940.By October, 1940, Blenheims fitted withA.I. Mark III had shot down six enemybombers. In November, 5940, the first killwith the improved version in Beaufighterswas made, and from then until the autumnof 1941 the main night fighter was theBeaufighter carrying A.I. Mark IV. Theinstallation in Beaufighters gained much ineffectiveness by use of a new modulatorproduced by an industrial developmentlaboratory. The maximum range rose tozo,000ft. and the minimum range fell toless than 600ft.

Radio LighthouseAir staff and scientific staff alike were

confident that controlled interception by dayusing the C.H. and C.H.L. systems woulddrive the enemy into a concentration of hismain effort on night bombing. They realisedthat the technique which was good enoughfor day control would not suffice for thecontrol of the night fighter even when he hadbeen equipped with the A.I. installationsunder development. It had long been feltthat a considerable improvement in accuracymight be attained by controlling the fighterdirectly from the ground radar station, thuseliminating the delay necessarily involvedin passing information to a Central FilterRoom controlling fighters. The improvementsattained in practice, however, were notsufficient to solve the problem of nightfighter,control. The radio lighthouse with itsPlan Position Indicator was now essential tosuccess.

The problem of attaining the radio light-house was a threefold one and three separateteams at the Research Establishments attackedthem. One had to develop an aerial systemof the same general nature as that for C.H.L.,but capable of being rotated continuouslyinstead of sweeping a limited sector. A secondgroup was attempting to solve the problem ofproviding more accurate height informationthan was yet available, while the third wasconcerned with the production of a suitabledisplay system. The lighthouse dream of1935 had described the kind of display systemthat was wanted, and the new team produced


it in an elegant and practical form, whichmarked one of the most revolutionaryadvances ever made in radiolocation. Theprinciple was that the distance scale on thecathode-ray tube started with its zero at thecentre of the tube and measured radiallyoutwards, so that the distance of an indicationfrom the centre of the tube was the distancefrom the radiolocation station to the targetconcerned. This distance scale was rotatedabout the centre of the tube, so that the angleat which it lay from the north point on thetube was the angle at which the narrowrotating beam from the rotating aerial layrelative to true north at that particular instant.Instead of the older device by which the radioecho made a notch on the distance scale, theecho now produced a bright spot on anotherwise dark background. Thus eachtarget was represented on the Plan PositionIndicator by a bright spot in the correct mapposition of the corresponding target, the mapbeing one showing the slant range and bearingof any point from the radiolocation station.

The practical realisation of the demand fora Plan Position Indicator, which may be saidto have come in about May, 5940, was a majorrevolution in radiolocation technique. Fromits first application in ground stations forfighter direction it passed to application inalmost every significant development ofradiolocation, on shore, in ship and in aircraft.

Ground Control of Night InterceptionThe solutions of all three problems just

mentioned provided the basis of the G.C.I.equipment (for the ground control of Inter-ception, particularly at night). BetweenMay and September, 1940, it was broughtto the stage at which actual fighter controlcould be demonstrated by T.R.E. to seniorR.A.F. officers ; in July the characteristics

officially agreed ; and another early " crashprogramme " in the long series of crash pro-grammes which have assured the timelyavailability of each new radar device, wasundertaken.

On October 75th a site for the first (mobile)G.C.I. was chosen; next day the equipmentmoved in from T.R.E., where it had beenbuilt; on the 18th it plotted its first aircrafttrack. A gruelling series of trials ensued,failure to cover certain vital zones had tobe cured, height -finding properties had tobe improved still further. Trials went on nightand day, a decision was taken to make sixsets even before the improvements had beenproven, and T.R.E., with invaluable helpfrom A.D.R.D.E., despatched the first of thesix on Christmas Day, 1940, the last of thesix on January 6th, 1941.

It was not long before the burghers ofBournemouth, and the guardians of security,were stirred by the passage through the townof a mobile set clearly marked with 48swastikas " notched on the butt."

Much of the credit for the successfulinterceptions which now came was due toA.I. Mark IV. New methods of trainingR.A.F. operators and improved servicing ofequipments paid good dividends. Speciallectronic devices which simulated on the

ground the process of interception weredeveloped at T.R.E., and T.R.E. technicianswere sent to squadrons to assist in R.A.F.training. These electronic devices were amongthe first of scores of synthetic " trainerswhich T.R.E. was to provide in helping theService to train the operators of many differentequipments, thus simplifying procedure andlit at the same time eliminating much of thetime which had been spent in training in theair. More than 2,000 aircraft and over toomillion gallons of petrol have been savedin this way.

The result of the new control system isIII seen in the statistics of enemy losses during

the first months of 1941. Our night fighters'

success increased steadily. in December,7940, they destroyed two enemy planes, withsix more probably destroyed or damaged.By March, 1941, the figures were 24 destroyedand 5o probably destroyed or damaged ; inApril, fighters accounted for 52 destroyed and88 probably destroyed or damaged ; in Maythe results were 502 destroyed and 572probably destroyed or damaged. In additionto these fighter successes, the number ofA.A. successes was increasing and formed aconsiderable proportion of the total. Thenumber of enemy sorties was about the samein each of the four months mentioned above

Radar in the Nary. This equipment seas designed to provideradar -controlled fire at enemy planes, using the main A.A.batteries, in large modern ships. It can also control the mainarmament of a destroyer against surface targets. Themodulator and receiver are similar to those used in the surface

gunnery equipment.

-and the overall casualty rate rose from lessthan per cent. to just under 7 per cent.On the night of May 10 -11th, the enemysent 34o aircraft to London, of which fightersdestroyed or probably destroyed 28 anddamaged a further so. It was obvious thatthe night blitz was more likely to result inthe destruction of the Luftwaffe than in theelimination of the Londoners and the invasionof Britain. Hitler decided to turn his attentionselsewhere.

CentimetricBut A.I. Mark IV had many limitations

which had worried its designers and its usersfrom the earliest days of A.I. work. It wasvulnerable to jamming by the enemy, and itwas also vulnerable to a very serious inter-ference by echoes from the ground below it ;the maximum range at which it could seeany enemy aircraft was in fact limited to theflying height of the A.I. fighter.

By far the largest reflector which sent backechoes to the A.I. receiver was the surface ofthe earth or sea ; therefore the A.I. operatorwould see depicted on his cathode-ray tube,firstly the transmitted pulse, then a clearspace with perhaps an echo from some nearbyaircraft, then a relatively huge echo,apparently several " miles " long and often

extending up to the farther edge of the tube.The " near " edge of this " ground return "marked the distance from the aircraft to thenearest part of the earth's surface, which is atthe nadir of the aircraft's position, and thisdistance is (very usefully) the " terrainclearance," or height above ground of theaircraft. (Hence, yet another application ofRadiolocation-the Radio -altimeter). Clearly,no small reflecting object, such as anotheraircraft, could be expected to make its feebleecho perceptible through the enormous," ground return " ; therefore, the maximumrange at which an enemy bomber could be

detected by the rl -metre A.I.of the fighter was equal to theflying height above ground ofthe fighter (and the minimumrange, that at which his echodisappeared in the " clutter "and the transmitter pulse).

This disadvantage of beinglimited in range by the" ground return could beovercome by the use of suchshort waves that a narrow -beam, no wider than that froma sharply -focussed motor -carheadlamp, could be used toilluminate the enemy, whilebeing kept clear of the ground,and so avoiding disturbanceof " ground return."

The story of the remarkabledevelopments in techniquewhich have made centimetrewaves practicable, and in them,have unified the art of radio -location, has already been toldin a preceding article.

The summer of 5940brought success to the"centimetric " experimenters.With the danger of night raidslooming ever larger, A.I. waschosen as the first applicationof the newly -won power oncentimetre waves.

The first aircraft fittedwith centimetric A.I. beganflights in February, 1941. Theradio beam projected aheadof the aircraft was narrow,and was made to scan a largearca of sky by giving a spiralmotion to the par a bolicmirror which focussed thebeam.

The success of these early centimetricequipments was so outstanding that a " crash "programme for a considerable number wasgiven to British Industry : this was a hard-and-fast programme with no hard-and-fastdesign, the latest innovations being incor-porated in production as soon as they becameavailable from the T.R.E. laboratories. Atthe same time T.R.E. began to make specialarrangements for teaching the new centimetretechnique to R.A.F. personnel and forintroducing the new A.I. (known as A.I.Mark VII) to the operators. A small groupof T.R.E. bodies was detailed specially forthis purpose and themselves learned thetheory of centimetre working and details ofA.I. Mark VII from their colleagues who haddesigned the equipment. The group becameknown as Post Design Services (PDS) ; theyhelped in the design and construction of testgear; they wrote technical manuals forthe use of R.A.F. learners ; and finally theythemselves fitted the first 36 A.I. Mark VIIaircraft and accompanied them to thesquadrons. This was the beginning of PDS,which expanded rapidly both in size and infunctions ; over 50 different equipmentshave been introduced to the Service by PDS.

(To be continued)


Power from Thermo -electricityThe Possibilities of Thermoelectric Couples By J. A. JOHNSON

TN spite of the broughams and river -launchesof 4o years ago, and the powered invalid -chairs-1 and tradesman's runabouts of

to -day, the long-distance electric vehicle stillremains a vision. The motorist still longs tobe rid of his gears and cold -starting troubles,and the non -motorist wishes for some cheapand simple way of avoiding the bicycle or bus.

Electric power is available from mainly

Fig. 1.-A simple thermo-electric couple.

three sources : driven dynamos, chemicalbattery action, and thermo-electric appliances.Accumulators, in spite of their weight, size,chemicals and deterioration, are still the mostefficient portable reservoirs of electrical energywe have. Assuming, perhaps wrongly, thatprimary and secondary batteries are unlikelyto be capable of much further improvement,the only alternative (pending the introductionof atomic energy) is to recognise that, in the

German Silver/ron

has given the writer sufficient output to drivea small electric motor, which moved a smalltruck carrying the thermo-pile and spirit -stove-in short, thermo electric -traction !

The thermal efficiency of this or, for thatmatter, of the most carefully designed units,is very poor ; roughly five per cent. or underas compared with about 14 per cent. forsteam and about 3o per cent. for internalcombustion engines, the majority of the heatbeing lost by spreading through the elementsand uselessly raising the general temperature.Moreover, thermo-piles share with accumu-lators the disadvantage of great weight perhorsepower.

On the other hand, any form of heat can beemployed : the household fire, the sun's heat,anything inflammable.

At the end of last century a relativelypowerful thermo-electric battery was con-structed which burned coal and produced5o volts at 5 amps. The method recentlyemployed by a manufacturer, in an effort toimprove thermal efficiency, was to heat eachcouple separately by a tiny hooded flame.

The goal is always to improve wattage percouple, with a reduction of weight and fuelconsumption. These three factors are, ofcourse, inter -related. The perfect coupleshould absorb all the heat, without itselfgetting hot, and deliver it as current. Themodern theory of electron pressure assists inclearly focussing the problem. Two metalsin contact exercise a neutralising electronpressure on each other (Fig. 3).

Fig. 2.-A number of thermo-electric couples brazed together.

light of modern knowledge, thermo-electricityis capable of further development.

Since its discovery by Seebeck in 1825,much attention has been given to thisinteresting subject in an effort to understandits true origin and also to apply it to practicalpurposes. To -day, it is still used for only veryfew and relatively unimportant purposes-furnace pyrometers, delicate laboratory heat -detectors, and as gas -heated batteries forradio sets.

If two thick wires (say, lin.) of dissimilarmetals, such as iron and German silver, arejoined by brazing in the form of a letter " V "and the two free ends connected to a galvano-meter (Fig. t); on heating the brazed joint,the passage of a very weak current will beshown in the detector. It is apparent that ifa number of these couples are brazed togetherin series and alternate joints heated (Fig. 2),a proportionately stronger current is generated.

Iron -German Silver ElementsWith little trouble a number of such rings

can be piled one above the other, separatedby flat asbestos rings, and the whole connectedin series. So arranged, 12o iron -Germansilver couples, with the centre at dull red heat

/5 V

Fig. 6.-Testing the sensitivity of a bar ofcopper sulphide.

When one of the junctions is heated thebalance is disturbed through the well-knownfact that, while the electron emission of metalsis greatly increased by heating, this varies fordifferent metals and alloys and for evendiffering crystalline structures of the samemetal, so that while one metal may have itsemir ion doubled by a to deg. rise in tempera -

6 6

iff

4 4 -4-= Nil -4-

4 =--/

Fire Clay rubewith

Cu S Pieces

Fig. 5.-Simple apparatus for demonstratingthe thereto -electric qualities of various

substances.

ture, that of another may be quadrupled by asimilar rise (Fig. 4).

Copper Sulphide ElementIdeal substances would therefore be those

which would conduct electricity well, butheat badly, and while one had very highemission with gentle heating, the otheremitted not at all. Copper sulphide does gosome way to meet these requirements, a barof this (produced by the direct combination ofa copper rod and flowers of sulphur in a heatedcrucible) being a relatively powerful thermo-electric element when coupled with copper orGerman silver, five such couples producing

volt at 2 amperes. This substance is,however, extremely brittle and friable owing

probably to its loose crystalline structure.This latter characteristic is, on the other hand,probably connected with its efficiency as it hasno thermo-electric qualities in powder form.If an external current of about 15 volts ispassed through one of these bars, via twocopper points, it will be found that it not onlyhas sensitive spots, like the galena wirelesscrystal, but that an area of bright red heat willdevelop round the positive electrode point

Cu 5 with veins of dull red heat radiating therefrom.In a very short time sulphur fumes appearand -the bar fractures along these veins therebybreaking the circuit. A microscope shows thata kind of minute inter -crystal arcing istaking place.

Figs. 5 and 6 show simple apparatus bymeans of which this and other similar interest-ing substances may be studied.

Electron MovementThe broader aspect of the inter -relation of

heat and electricity in conductors becomesevident the further investigation is carried.At the risk of over -simplification, this may besummarised as the difference between chaoticand orderly electron movement. That the

(Continued on page 219)

9-81s

6

11113.../

43 -4-

),% 6-24°

Figs. 3 and 4.-How two dissimilar metals exercise a neutralising electron pressure on each other.


Rocket PropulsionRocket -assisted Take -off : Successive -feed Powder Motors

By K, W. GATLAND

(Continued from page 176, February issue)

AGREAT deal has already been saidof the development of successivelyloaded powdef motors, but the units

concerned have largely been the outcome ofresearch in the U.S.A.

In Britain, similar research has been con-ducted by the Astronautical DevelopmentSociety, and this has involved investigationsof the recharging mechanisms for both theslow -burning and rapid -burning powders.

The principal difficulty associated withpowder fuels has always been their limitedduration of firing, and in the developmentof the successively loaded motor much hopeis held to remedy this deficiency.

Assisted Take -off Rocket UnitsThe use of rockets to assist fighter aircraft

and heavily laden bombers and transports

4 PetcNon Carriage at forwardPos,tion

Reaction Carriage at ;9earwarriPosition

Fig. 56.-Diagrams showing two positions of animproved cartridge injector.

into the air without the need for longrunways is to -day common knowledge.

Almost without exception the unitsemployed are simple cordite rockets. Thestandard charge contains 2616. of propellentwithin a steel casing of about 401b. weight,4oin. long and 5in. in diameter, with a ;sin.wall thickness. Short nozzles are fitted,. 4in.in length, the throat to mouth diametersenlarging from approximately tin. to 4in.

The thrust yield of these charges is slightlymore than r,000lb., and the energy per lb.of cordite, therefore, a little greater than4ilb.

The rockets are mounted in batteries oftwo to four, generally either side of thefuselage, close in to the wing roots. Theyare usually capable of maintaining a thrustconstant for about four seconds, and, onceexpended, automatically release from theirmountings and drop away.

In trials carried out in the U.S.A., a navyAvenger, was fitted with four " Jato " assist-ing rockets, each capable of a thrust of33o h.p., and it was found that these cutdown the take -off run by as much as 60 percent.

It is of interest to note that the Sanderrolb. powder charges, used by Fritz vonOpel in his rocket glider of 1929, eachdeveloped a thrust of531b., effective for 25seconds. Other singlecharges produced bySander were capable ofthrusts exceeding 600lb.,but only for three orfour seconds.

A high thrust, it willbe appreciated, is onlypossible at the expenseof the effective thrustduration and the burn-ing rate can be moder-ated by the type andconsistency of thepowder employed.

Because of the neces-sarily limited durationof high thrust powder

charges, it isobvious thatsome form ofconstant feeddevice, able

to fire several charges -111

in quick succession,would be a valuablerefinement. Before go-ing on to discuss unitsof this kind, however,a word about an inter-esting liquid fuelaccelerating gear, de-veloped in 1943 andused extensively bythe Luftwaffe.

The Walter Bi-fuelA.T.O. GearThe Germans

sought to overcomethe limitations of thepowder charge by theuse of a bi-fuelassisted take -off unit,known as the Walter109-500.

The device em-ployed 8o per cent.pure hydrogen perox-ide with a perman-ganate catalyst, theperoxide beingcontained in aspherical tank andfed to a singlecombustion cham-ber under pressurefrom air bottles.Its fully chargedweight was only Nozzto600lb.

The motoroperated at anaverage thrust of1,2oolb., the powerlasting from 24 to28 seconds.

Two of theseunits were fitted,one below eachwing, being jetti-soned and para-chuted to the

"Strut Psychro-meter." An instru-in en t used onmeteorologicalaircraft for record-ing pressure, tem-p er a t ure, andhumidity. - Courtesyof the MeteorologicalOffice, Air Ministry.

Combustion clamber

areech blockRoan,'bevr4,9_

Rexiblesedimy 6,7,9

prrrner

Combustionchamber

Cd5obturator

Nitro-cellulose'cartridge'

Nozzle(8' flare

angle)

Fig. 58.-Detail of fir ng chamber and sealmechanism of rapid fire " cartridge" motor.

ground for re -use, once combustion hadceased. Since only " chemical combus-tion " took place within the chamber, thesame unit, recharged, could be used severaltimes before corrosion took serious effect.

A modified version of the Walter 109-50owas fitted in the Hs. 293 " glide -bomb,"used for attacks upon Allied shipping.

A Successive Feed Motor for Slow -burning PowdersAn outline of the more critical design

problems to be overcome in the evolvementof a suitable device has already been givenin the references to Professor Goddard'searly researches with rapid -burning powders(PRACTICAL MECHANICS, August, 1945, pp.373-4), and it will be recalled that, althoughmuch in detail has been previously conductedconcerning chamber and nozzle efficiencies,information is entirely lacking of the reload-ing mechanism itself.

Work towards evolving a small motor,capable of the repeated injection of quanti-ties of slow;burning powder to a single com-bustion chamber, was commenced in 1941,and credit for this and subsequent develop-ment is largely due to Mr. A. M. Kuneschand the writer. The outcome of an initialsurvey was a first self-operating design inwhich powder fuel was intended to be fedin the form of "cartridges " {Fig. 57).

With reference to the diagram, it willbe seen that the unit is made up of thefollowing components: combustion chamber,door, breech, cartridge, pump, pneumaticjack, and injector rod.

The " injector was designed around aspecially prepared " plastic cartridge " whichhad no separate case and burned away corn-

Compressed-alr bottle

_Trip operatedcheck valve

1

Double extensionpneumatic jack

--------Cartridgeentry triggerand seal

- -1-Cartridgechute

Fig. 57.-The improved cartridge injector for slow -burning charges(Astronautical Development Society, 1943).


pletely. The desired structural form resultedfrom an organic admixture to certain fuelpowders, and using this process it was foundthat rocker propellents could be farmedreadily into any desired shape or size.

Two views of an ex-perimental rocket motorto the design for a rapid -firing cartridge injector.It has been used as aproving motor for testingsingle charges. (Astro-nautical Development Society, 5943).

Experiments with charges of this naturehave shown that no residue remains, afterfiring, it being found that ash produced incombustion only condensed outside -thenozzle, This is particularly important inview of the fouling which occurs after thefiring of gunpowder, and which would seri-ously impede the proper function of arepeating mechanism.

Apart from the special powders tested, itis also possible to bond nitro-cellulosepowders-cordite, for instance, may be con-veniently formed by the admixture ofacetone.

An impression of the " injector " can bebest gauged from an explanation of itsoperation. The firing sequence is as follows :a cartridge is initially primed to the combus-tion chamber when the "reaction carriage "is at its foremost travel-as shown inFig. 56. The chamber seal door is then closedby a cam action and the cartridge fired,causing the complete unit to recoil alongrunners to a bearing plate. During thisaction air pressureis transferred fromthe supply pump(situated beneaththe carriage) to thepneumatic jack,which actuates theinjector rod and re-tains it at the rearof the carriage. Asecond cartridge isthen free to enterthe breech.

Once the thrustof the primed chargehas fallen below acertain value, recoilsprings return thecarriage to itsoriginal position,pressure being trans-ferred back to thesupply pump, whileair is forced outinto the other sideof the injector jackto move the rod for-ward. The door isthen rapidly openedand closed to allowthe second cartridgeto enter for combus-tion. From t hispoint the operatingcycle is continuedautomatically.

T h e conclusions

thrust Itine -'

of the initial survey gave clear indicationthat the two types of powder-slow andrapid burning-would require entirely dif-ferent injection mechanisms. In view of this,it was decided to proceed first with the slow -

burning powder motor as thesystem originally developedwas obviously not suitable forrapid firing.

An Improved " CartridgeInjector"The second design was

prepared in more detail and

presented an altogether more practical solution.Perhaps most important of all, the effectivesealing of the firing chamber-a problemignored in the early design-was most satis-factorily overcome. Another refinement wasthat the recoiling feed action was eliminated.

The improved " cartridge injector " (Fig.56), though basically the same as the original,incorporated several entirely new features.It comprised the following main items :combustion chamber, breech, cartridgeentry chute, cartridge entry trigger andchute seal, pneumatic jack, check cocks(two required), compressed air cylinder, andbreech bloCk/injector.

As may be gathered from the diagram,the motor is designed to operate under con-trolled pressure from an air bottle. The airis fed through trip -operated control cockswhich alternately direct pressure to movethe breech block/injector backwards andforwards under the action of a pneumaticjack. As will be seen from the diagram,the breech block, which seals the chamber,also forms part of the injector movement.

Second cartridger----10 in delivery tube-

N\he/a in place bya frrg9er

IP Cammeth

Breechblockengaged

View onBreech 11 Breech

62c_15. (Posermechanism 8 armomitted for clarity(1) all views)

ICS

Sequence T. --Cartridge primedto chamber and

fired.

Thrustring rdm

track

/Breechblockc/a -engaged

View on Breech- 8 Breech Bloch,

Sequence 2.-Motorrecoils and camgroove rotates breech

block (see section).

trI9gerreleased by \ ----

aacaemdcridt;nd ert \enters chamber 114

under reactive.mpu/se

QQ1 1P

-

0

Or1I iI o,I #0 ,0 d

At the rearmost travel of the injector acartridge is allowed to enter the breech, Theair pressure is then applied to return thejack piston, which pushes the injector for-wards and inserts the charge. The breechblock at the injector head is then screwedin to seal the combustion chamber underthe action of the " Archimedes screw," andthe cartridge electrically fired.

Immediately the thrust of the charge com-mences to decline, pressure from the airbottle moves the jack piston backwards, andthe injector head automatically unscrews andtravels to the rear, allowing a further chargeto rise into the breech.

It would probably be necessary to incor-porate vents around the chamber seal toprevent " blowback " of thrust pressure ° asthe chamber is opened preparatory to theinjection of a fresh charge. Otherwise, thegas temperature may be sufficient to ignitethe charge before its entry into the cham-ber. The unit described is intended to firefive three -second cartridges, but for unitsemploying more charges it would be neces-sary to jacket the combustion chamber withliquid coolant.

Whether or not an A.T.O. system of thistype would be preferable to fixing the samenumber of single charges to fire in sequenceis debatable. The one principal advantageof the reloading device is that the thrustline is constant, and as reloading would bealmost instantaneous, the whole questionlargely resolves into a matter of reliability,weight and installation space.

The Rapid-fire Rocket MotorThe rapid -firing cartridge motor is

altogether different from the units previouslydescribed, having been designed to powera light, high -altitude sounding rocket.

In this arrangement the cartridges are fedat the rate of zo per second, but each chargeweighs only 8oz., as compared with thecharges of several pounds specified in theslow -firing designs. Because of this, themechanism which feeds the cartridges canbe appreciably lighter, and it is this factorthat largely accounts for the high rate offire. It has, in fact, been estimated . that

Cam. -Track

View m Breech(Breech blockhinged Vert()

Sequence 3.-Motor furtherrecoils and breech block issnapped clear for entry of

fresh cartridge.

Fig. 59.-Part sectional diagrams showing operation of the rapid-fire "- cartridge" rocket motor.(Combined British Astronautical Societies, 5944).

Thrusthoe

Thirdcartridge entersdelivery tube andheld by trigger

View on Breech8 Breech Block

Sequence 4.-Motorpartially returned bysprings. Breechblockis snapped to, andfurther counter -recoilengages breech andfires cartridge - as

sequence r).


the total weight of the moving parts wouldnot exceed 15oz.

The combustion chamber (Fig. 58) isdesigned to recoil along runners, and thecartridges are fed by the inertia. There isan opening breech -block to allow the cart-ridges to enter the chamber, which is rapidlyopened and closed under the action of a cammechanism operated by the recoil.

The chamber is returned by strong springswhich compress as the motor recoils underthrust, and the charges, having separateignition primers, are fired electrically by asimple " make and break " circuit.

The breech -block is constructed with inter-rupted threads. This enables the breech tobe disengaged and re-engaged .by a slightturn of the roller bearing to which the hingedarm of the breech -block is attached.

The Combustion Chamber and NozzleThe combustion chamber is particularly

small, its internal length being only tin. bylin. diameter. These surfaces are finelymachined and polished to reduce frictionallosses, and thus any excessive heating of thechamber is avoided.

A high operating efficiency is thereforemaintained over the entire period of com-bustion, and while it is rare for a liquid -fuelled motor to greatly exceed a chamberpressure of 5oolb./sq. in., the rapid firing" cartridge " motor is designed to permit theexceptionally high pressures of 30 to 45thousand lb./sq. in.

This largely accounts for the highefficiency, which is, of course, due to therapidity of combustion and the greater expan-sion and less dissociation of the gases.

To suit these conditions the size of themotor is limited, but, nevertheless, the dimen-sions of the unit here discussed are wellwithin the bounds of the practical. Indeed,the thermal efficiency would be improved byslightly " scaling up " the chamber, due tothe reduced heat loss. This is because thechamber area increases by four to the weightof the charge, eight times.

A high -expansion tapered nozzle, 7.25in.long, is fitted which embodies an 8 degreeflare angle, expanding from .i25in. at thethroat to slightly more than tin. at the mouth.It is not quite a straight taper, as at themouth end the angle is decreased to forma short parallel length, and this refinement-originally adopted by Professor Goddard-ensures that the high -velocity gases fill thecross-section throughout the entire nozzlelength. Without this change in contour adiscontinuity of flow would be produced atthe points where the gases leaVe the wallof the nozzle and result in the formationof eddies with a consequential loss ofunidirectional velocity.

In comparison with the machine-gun-auseful guide in this work-heating effectswould be less critical. In the gun the bulletcreates considerable friction and confines thepropelling gases in the barrel (at a tempera-ture of 2,000 deg. C.), whereas in our par-ticular case there is no friction save thatof the gas itself, which escapes almostinstantly.

It is thus obvious that the rocket motorwill permit the firing of considerably morecartridges than a machine-gun before gettingto critical heat-the temperature at which thepropellent is ignited merely by contact withthe combustion chamber.

Explanation of DiagramsThe diagrams (Fig. 59) represent the firing

sequence of the motor, and is self-explana-tory. Sequence " a " shows the motor asiz appears at its rearmost travel, a cartridgehaving just been fired. The breech blockis, of course, engaged in this position, and

a fresh cartridge is held in place at the bottomof the feed tube.

In the second view the motor is shownpartially recoiled, and it will be seen thatthe breech -block has been rotated so thatit is completely disengaged under the actionof the cam tack.

The third sequence depicts the motor infull recoil, with the breech -block snappedclear and the feed trigger released to allowthe second cartridge to enter the chamberunder the inertia of recoil.

Finally, the motor is shown partiallyreturned by the recoil springs (these areomitted in the diagram), the breech -block

The combustion chamber of the bi-fuelWalter 109-500 assisted take -off unitdescribed in this article. Note thehelical mixing vanes around the centralsupport tube. The propellent entersthrough a stainless steel nozzle at the head, and thrust is derived through chemical

reaction resulting from 1-150, and calcium permanganate.

than the test types, the maximum figureshould be nearer the mark.

Using .ioz. cartridges, the jet flow worksout at 21oz. per second, and assuming ajet velocity of 7,5ooft./sec.' the thrust wouldbe approximately 3611a. Although the jetflow and thrust values are not great in com-parison with other motors, the fact that thechamber is of midget proportions and thecomplete unit so very light ensures a highoperating efficiency.

A Solid -fuelled Sounding RocketThe possibilities of the unique cartridge

motor in a sounding rocket arrangement are

being snapped to, but the threads not yetengaged in the breech. At this point a selec-tive mechanism allows a third cartridge toenter the delivery tube.

At the rearmost travel the motor appearsagain as sequence " a," the breech -block re-engaged, and the second charge fired as thefirst.

PerformancePrevious tests of single -shot motors of

similar chamber and nozzle forms haveshown that it is reasonable to expect jetvelocities of 7,000 to 7,5o0ft./sec., and sincethe chamber proposed is somewhat larger

Parachuteromparm-en

Rudder

HecoitGuides

Gyroscope 6relay device

kittnimentr

CelleIvrtube structurecontetnrog 42801 oz fuel cartridges

fins

19 Cartridgecelluies

Section A. -A.

Selective teedmechanism

Electric servomotorscontrol mechanism

Certr/cide feedtube

ReactionMeter

fleClill *foregocells

Fig. 6o.-Suggested layout for a successivelyloading " cartridge" rocket.

illustrated in Fig. 6o. As will be seen,the unit can be very compactly accommo-dated, and there appears no reason why suchan arrangement should not prove highlyeffective.

In the projected design the fuel containercomprises 19 individual -Ain. i/dia. cellules,arranged on a honeycomb plan for maximumstructural strength and fuel capacity.

Basing the size of the rocket on aolb.of fuel (or 1,280 cartridges), it should bepossible to build the cellules and shell ofbonded plastic, as affording a ready finishand greater resistance to denting than amuch thinner metal case and tube structureof the same weight. A plastic case and thedesired number of cellular feed tubes wouldweight about 51b.

The motor, having a weight of 21b., plusalb. of instruments, makes the total for themain components in the region of 181b.

The rocket would have an initial accelera-tion of lg. and a final acceleration ofapproximately 3g., and, using 1,280charges, the firing duration would be 64seconds.

(To be continued)

AUTOMATIC GUN COCKERANEW device which has been submitted

to the British Patent Office concernsguns in which cocking during firing iseffected automatically by gas pressureobtained from the barrel of the gun.

In the larger guns, it is stated by theinventor, after the supply of ammunition hasbeen exhausted and a fresh supply has beenintroduced, the initial cocking cannot beeffected by hand. It has been subjected topneumatic treatment, but this method,asserts the inventor in question, is some-what complicated.

The object of the new device is animproved and simplified means for the initialcocking of the gun.

The invention comprises a hydraulic pumpsupplying pressure fluid to a cylinder con-taining a plunger which performs the cock-ing operation. There is also a plunger -typeautomatic valve loaded through a leverhaving two positions: (1) where the valveis closed and loaded against the pumpdelivery pressure and (2) where the valveopens a by-pass passage to release the pumpdelivery pressure and is not loaded to returnto its service position, so that such return.must be effected by hand.

212 NEWNES PRACTICAL MECHANICS March, 19 46

The Mechanics ofMeteoPOloAy--4Cloudbursts : Snow : Wind Speed and Direction

By G. A. T. BURDETT

(Continued from page 563, February issue)

CLOUDBURSTS are nothing morethan thunderstorms of an exaggeratedform.

We have seen that the cumulonimbuscloud requires strong up -currents of warmair to support it. In fact, such large quan-tities of water which are contained in thethundercloud can only be supported bystrong up -currents. Should these ascendingcurrents for some reason suddenly cease,most of the water content would, by forceof gravity, descend to the ground at once.When this happens we have what is termedthe " cloudburst."

These occur chiefly in hilly and moun-tainous districts. When the cloud passesover the hill on these occasions, the ascendingcurrents of air decrease in strength and thecloud releases its water.

This phenomenon of variable air currentsis particularly apparent when travelling in aglider towed by powered aircraft over hillydistricts. On occasion the glider has beenknown suddenly to drop 200-3ooft. withoutwarning.

Some years ago, as a result of a "cloud-burst," the watersheds of a hydro -electricscheme in North Wales were overloaded withwater, the dam burst, wrecked houses andcaused several casualties, some fatal, in thevalley below.

HailNormally, we consider that water turns to

ice (freezes) once its temperature dropsbelow freezing point (32 deg. F.). Exper-ience has shown, however, that such is notalways the case. Water drops can exist inclouds in liquid form with the temperature

28* F

Snow region

A'

s`..) 30° r

31°F 31°F

Super cooled water drops

3/"F

32°8

32'F33°F

uid water drops

35*

C 38°F

Fig. 26.- Thundercloud (cumulonimbus) showing three distinctportions-snow region, super -cooled water drops, and liquid

water drops.

as low as o deg. F. These are termed super-cooled water drops. Once they come intocontact with anything such as an aircraft,or even a small water droplet, the super-cooled water turns to solid ice.

Clouds of great vertical extent, viz., cumu-lonimbus, which are separated by large,upward currents of air, usually comprisethree, though not distinct, portions (Fig. 26):The top portion, known as the snowregion," where the drops are frozen intoice crystals ; the centre portion, which com-prises super -cooled water drops ; and thelowest portion, which comprises liquid waterdrops of a temperature above freezing level.

The portion of the cloud between A and Bcomprises a mixture of both ice crystalsand super -cooled drops. When one of thelatter impinges against the ice crystal itimmediately solidifies into soft ice. In doingso the drop traps a little air, becomes largerand falls through the super -cooled region,still growing. When it reaches the lowerregion it comes into contact with water dropsat a temperature of 32 deg. F. (just abovethe super -cooled temperature), the waterdrop is deposited on the ball of soft ice andfreezes as a coating of hard, transparent ice.The ball then falls to the ground as hail. Ifa ball of hail is cut open it will reveal a coreof soft ice surrounded by this hard layer.

The hail does not always fall direct to theground; but is caught up by the strong risingcurrents of air in the cumulonimbus cloud andis lifted into the top region. It then fallsagain and goes through the same process, afurther layer of soft ice, and then a coatingof hard transparent ice. This may happen anumber of times until the air currents can

no longer support it. If theselarge hailstones are cut openthey will appear as concentriclayers of soft and of hard trans-parent ice.

Hail often falls as soft ice(soft hail) when it his beenformed in the region where thetemperature of the drops is at32 deg. F. and no upwardcurrents of air have carried themback into the cloud.

SnowSnowflakes are formed from

one or more ice crystals. Whenwater vapour condenses attemperatures even below freezingpoint, liquid drops first form,which crystallise later. In theupper region of the cumulonim-bus cloud we have seen thishappen, while in the centreregions the droplets remainliquid and are " super -cooled."

Now, water crystallises inhexagonal form. Snowflakesmade up of a number of thesecrystals take on a variety ofshapes which, when examinedunder a microscope, showperfect symmetry of form and

Fig. 27. - C u p-anemornater, a windindicator. The windenters the hollow ofthe cups, which revolveon a spindle. Thedistance travelled bythe cups is measuredon the counter. Overan interval of time,e.g., minute, the speedof the wind is obtainedby reference to a chart.

(Photograph by Negrettiand Zambra.)

often make most beautiful patterns.When snow falls at high temperature the

flakes are large and very moist and are builtup of a number of crystals. When the tem-perature is low the flakes are smaller and" dryer." When the temperature is farbelow freezing point (32 deg. F.) the pre-cipitation is snow dust," as dry flakes donot readily combine.

SleetSleet is largely partly melted snow, and

is sometimes due to the precipitation of bothsnow and rain. A temperature increase nearthe ground is often the reason for the sleet,since the snow, as it reaches the ground,passes through layers of air of higher tempera-ture just above 32 deg. F., which causes thesnow to partially melt.

When Snow May be ExpectedSnow, which, as we saw above, is really

only frozen water droplets before precipita-tion, can be expected at any time when athigh temperature rain would be due, viz.,the passing of a depression, instability ofthe atmosphere or the condensation of moistatmosphere, due to its coming into contactwith cold, high ground.

Too Cold to SnowThe layman is often heard to remark in

winter that " it is too cold to snow." Thisadage is true in fact, but only when the cold,dry polar air is passing over the area.

If this is followed by a depression from theAtlantic when warm, moist air comes intocontact with the colder polar air, the formercondenses, forms cloud and either rain orsnow descends; depending, of course, uponthe temperature.

Glazed FrostSometimes in Great Britain, but on rare

occasions only, the roads, pavements, sur-faces of the buildings and practically every-thing are coated with a layer of glassy iceknown as glazed frost.

Traffic is brought to a standstill, and it isalmost impossible for a pedestrian to proceedwith safety. Electric railways which runabove ground are particularly susceptible toglazed frost since the ice acts as an insulatoron the conductor rail and the train cannotobtain the necessary current to drive it.

One of the worst glazed frosts recorded inGreat Britain occurred on December 21st,5927, when traffic was brought to a standstilland a number of accidents were caused.

Glazed frost is due to the following :


rendency of wind directiondue to pressure distribution

Surface wind

Fig. 28.-Direction of gradient wind, owing to tit,. geostrophicand cyclostrophic effects of the earth's rotation, flowing in ananti -clockwise direction around a depression in the northernhemisphere parallel to the isobars, as indicated by the parallelblack arrows, at a height of 1,000ft. to 1,5ooft. (Note.-Surfacewind flows at an angle of 3o deg. to the isobars due to the friction of

the earth's surface.)

The temperature of the ground must bebelow freezing point. Precipitation in theform of rain at a low temperature collectson the surface and immediately freezes. Some-times the drops are super -cooled, but generallyit is the temperature of the surface (ground,etc.) which determines whether glazed frostwill occur or not.

When glazed frost forms there is usuallyan increase of temperature over the area.The cold water drops pass through a com-paratively warmer temperature, but onapproach to the ground the temperaturedecreases. At ground level the temperatureis below freezing point. The ground frostwhich often follows snow, which is meltedin the heat of the sun during the day, isfrozen and resembles glazed frost. This isnot, however, glazed frost, but just a normalground frost which occurs when conditionsare favourable, as pointed out earlier.

Formation of RainIt has been shown that the moisture content

of clouds and even large water droplets aresupported in a cloud by rising air currents.The nimbostratus cloud, which is a rain cloudof the layer type, does not require strongupward currents to support it. ' When themoisture in the air has condensed, due to itstemperature falling below dew point, and thecloud forms, small water drops which have adiameter in the order of 0.002 mm. are readilysupported by the small upward current ofair. These are then carried farther up throughthe cloud, and as the temperature decreasesthe water drops increase in size until theyreach a diameter in the order of 0.2 mm.By force of gravity these fall to the earth inthe form of rain, since the upward currentsof air can no longer support them.

The WindIn the British Isles the wind is almost

constantly changing in both force anddirection.

The cyclist will set off on a clear day andbefore long he will find he is cycling against ahead -wind of a fairly high speed. On hisreturn journey he may, to his dismay, findthe wind has now changed to the oppositedirection, and he again has to cope with ahead -wind.

Also, at a given time, the wind, or winds,

will be blowing in differentdirections at varyingspeeds in different placesnot far apart.

Direction and force ofwind also vary withaltitude. At ground levelthe air may be calm,while at so,000ft. strongwinds will he blowing.

Wind, which is themovement of massesof air, is largely causedby the following :

(s) Changes in thevariation of the tempera-ture of air masses overland and sea;

(2) The movement ofair from areas of highpressure to areas of lowpressure;

(3) The movement orpassage of frontalsystems.

Wind, like the formationof clouds, provides a goodindication to themeteorologist of the typeof weather which may beexpected in the immediatefuture (viz., up to 24 hoursin advance).

Before attempting tofit wind into the general

weather picture, it is necessary to under-stand its most fundamental principles.

Measuring WindThe direction of the wind at .the earth's

surface is usually given by the meteorologistin the points of the compass, viz., north,south, east, west, north-east, and so on.This direction is that from which the wind isblowing and not vice -versa. The commonweather vane points in that direction-that is,up -wind. This vane is so constructed that thearrow head offers the least resistance to thewind, and is therefore against the wind, whilethe thick end will be down -wind, as it offersmore resistance.

When observing the general wind direction,it is important not to place too much relianceon the ordinary weather vane unless this isisolated, since it may indicate only the localwind. For instance, should the vane be sitedbetween two high buildings, the wind willgenerally, irrespective of its true direction,blow between the buildings and give theobserver a false reading.

Wind blowing between hills, along a valley,or over the coast may not necessarily coincidewith the direction of the general wind, andshould therefore be treated as local wind only.

While the winds are light and variable, theweather vane is useless. In these circumstancesa good indication of wind direction is thatof smoke.

A close observation ofthe flight of birds isrecommended whenstudying wind direction.It will be noticed thatbirds, except the smallerand younger ones, alwaysland and take off againstthe wind. Pilots inaircraft also, of course,manipulate their aircraftlikewise.

Wind SpeedThe speed of wind is

measured in miles perhour on the land, and inknots at sea. Ground temp

Where wind -measuring Fig. 29.-Katabatic wind. By night, reaching maximum about 4 a.m.instruments are not G.M.T., cold air from top of hill falls down slope into valley andavailable, more general forces warm air in the !-alley to rise, as indicated.

terms may be used, such as light, moderate,strong.

To assist in the accurate estimation of windspeeds, the Beaufort Scale is used (seeaccompanying scale). This scale, whichbears his name, was devised in 5805 byAdmiral Sir Francis Beaufort, then hydro-grapher to the Navy. For easy reference, eachgroup of wind speeds is allotted a Beaufortnumber. From the table it will be seen thatForce 3 on the Beaufort Scale refers to a windspeed between eight and sz miles per hour,and is termed a gentle breeze, indicated bythe constant motion of leaves and twigs.Small flags are also extended by wind ofthis velocity.

Plenty of practice is necessary beforeaccurate estimates may be made. Wherepossible a check should at first be madewith wind -measuring instruments, viz.,anemometers (Fig. 27).

Wind velocity usually increases with height.Therefore, that observed at ground level is oflittle use for estimating that at an altitude of,say, 3,000ft. Here the velocity of the cloudsmoving across the sky should be noted. Onemethod of doing this is by observing theshadows of clouds moving over the ground.

Not only does the velocity of wind vary atdifferent heights, but also its direction. Thismay be proved by comparing the direction ofthe cloud movement with the surface wind.Quite often the wind at high altitude will beblowing in the opposite direction to that atthe earth's surface.

Veering and BackingWhen the direction of the wind changes in a

clockwise direction it is said to be veering.For instance, if at 8 a.m. the wind is blowingfrom the south, and at so a.m. from thesouth-west, the wind has veered from thesouth to the south-west.

Conversely, when the direction changes inan anti -clockwise direction, it is said to bebacking. If, therefore, at to a.m. the windhad changed to south-east instead of south-west, it would have backed from south tosouth-east.

Wind DirectionSince wind is largely caused by the move-

ment of air masses from areas of high to areasof low pressure, we would expect the wind toblow in a straight path from one area to theother, as represented by the dotted line inFig. 28. In practice this is not so, for it isdeflected to one side by the rotation ofthe earth.

In the northern hemisphere the deflectionis to the right, and in the southern to the left.This deflection is known as the geostrophiceffect. As a result of this curved movementof the air a further force is present, known asthe cyclostrophic effect, due to the gyroscopicproperties of the moving masses of air, whichtend to force the wind off the curved path.

Ground temp40. F Cold an descending

down slope

40.F

Warm air rising

11 I

48 F


The wind now will move along the isobars,that is, parallel to them and not at right angles,from the areas of high to low pressures. Thediscovery of these facts led to the formulationin 1853 of a law by Professor Buys Ballot, ofUtrecht, now known as the Buys Ballot'sLaw.

This law states that in the northernhemisphere if you stand with your back tothe wind, the area of low pressure is on theleft. In the southern hemisphere it is theother way round. From Fig. 28 it will beseen that the wind blows in an anti -clockwisedirection around an area of low pressure.Conversely, the wind blows in a clockwisedirection around an area of high pressure.This again refers to the northern hemisphere,the reverse being the case in the southern.

Although winds follow the direction of theisobars, this is only strictly true of winds abovethe height of about 1,000ft. Below thisheight, friction of the earth's surface, treesand so forth, tend to slow up the wind and,since the cyclostrophic effect is reduced, thewind is freer to follow a more direct pathbetween the two different areas of pressure.The result is that the wind blows across theisobars at an angle of approximately 30 deg.towards the area of lowest pressure (Fig. 28).

From the above, it will be appreciated thatwind bears a direct relationship to thedifference in pressure of the atmosphere.

Because of this, meteorologists are able toestimate the speed of the wind in differentparts of the country (or the world) at giventimes by observing the atmospheric pressuregradient at these points.

The pressure is observed and recordedat the various observation posts, andparticulars arc circulated to the meteorologicaldepartments. They are then noted on specialcharts provided, and lines (isobars) are drawnbetween the points of identical pressure.These isobars, when completed, are similarto contour lines on topographical maps, butrepresent gradients, not of heights, but ofpressure. While on a topographical map linesdrawn close together indicate steep gradients,those on the weather map, or synoptic chart,as it is termed, indicate the velocity and thedirection of the surface wind. The closer theisobars, the higher the velocity of the windat that part.

Diurnal Wind VariationDiurnal, which means the passage of time

over a period of 24 hours, is used in this caseto record the probable wind variation whichnormally occurs from day to day.

Over a considerable period of time,meteorologists have recorded that during thedaytime the surface wind usually veers andincreases in speed, while the upper wind,viz., r,sooft. and above, tends to back and

*i

decrease. As nightapproaches the reversehappens and thesurface wind drops andbacks, while the upperwind tends to veer andincrease in speed.These variations will,of course, be alteredby weather changes,the passing of fronts,seasons, and so forth.Effect of Tempera-

ture of Air MassesIt was shown earlier

that the sun heatingthe ground, which inturn heats the air,causes masses of warmair, e.g., there -palcurrents, to rise intothe atmosphere. Thisdisplacement of air is,of course, one of thedirect causes of wind.

It was further shownthat substances suchas sand, earth and rock heat up more quicklythan woodlands, areas of vegetation and thesea and lakes. Conversely, the former

Warm air rising

10 Mph.

Land

31.-Sea breeze.

ThCoastal cumulus cloud_1 often causes coastal

&tree

k5 Melt

/5 Mph.

See 52'

By day, reaching maximum velocity at about3 p.m.

substances give off their heat quicker thanwoodland and the sea, etc. This variationin heat dissipation also causes a variation in

THE BEAUFORT SCALE OF WINDObserved Effects

FORCE

Beau-fort

Num-ber.

Generaldescription

of windFor use inland For use at sea

Wind strengthin m.p.h. atabout 3o feetabove ground

level.

0 Calm .. .. Smoke rises vertically Sea like a mirror .. .. .. Less than t

t Light air .. Smoke, but not windvanes, show winddirection

Scale -like ripples .. .. .. 1-3

2 Light breeze .. Wind felt on face ;leaves rustle ; windvanes moved

Small wavelets ; glassy crests .. 4-7

3 Gentle breeze Leaves and smalltwigs moving con-stantly ; small flagsextended

Large wavelets ; crests begin break ;a few white horses

8-12

4 Moderate Dust and loose paper Small waves become longer; white i3-18breeze raised; small

branches movedhorses fairly common .. ..

5 Fresh breeze .. Small leafy trees sway Moderate waves with pronouncedlength ; many white horses. Somespray

19-24

6 Strong breeze Large branches inmotion ; whistlingheard in telegraphwires

Large waves form; white foam crestsmore extensive everywhere

25-31

7 Moderate gale Whole trees in motion Sea heaps up and white foam frombreaking waves is blown off

32-38

8 Fresh gale .. Breaks twigs off trees Moderately high waves of greaterlength

39-46

9 Strong gale .. Slight structural dam-age occurs chim-ney removed

High waves; dense streaks of foamalong the direction of the wind

47-54

to Whole gale .. Trees uprooted ; con-siderable structuraldamage

Very high waves with long, over-hanging crests ; foam in greatpatches

55-63

it Storm.. .. Very rare; widespreaddamage

Exceptionally high waves; sea corn-pletely covered with foam

64-75

12 Hurricane .. Very rare .. .. Air filled with foam and spray; seacompletely white with driving spray

Above 75

NOTE.-The velocity of the winds given is only that for Soft. Above that height the winds are stronger

45*F

Cold air descendingnto valley

Fig. 30.-Anabatic wind.By day, reaching maxi-mum about 3 p.m.G.M.T., cold air fallsinto the valley and forceswarm, light air up theslope to the warm hill -top.

the thermal currents of rising warm air, theeffect of which is to cause variation in windspeed in different places.

Most local wind variations are due to thetemperature effect. These " temperature "winds are termed Katabatic, Anabatic andsea and land breezes.

Katabatic WindsKatabatic is the name given to winds

which usually blow down the hill or mountainGround temp.


acret

Fig. 32.-Land breeze. Bynight, reaching maximum

velocity at about 4 .nz.

Warm wr r,sIng

111

Sea 17r,-_-_--7-50°F

side at night, following a hot day. During theday the temperature of the land will have beenraised by the heat of the sun. When nightfalls, the highest points, viz., the tops of thehills and mountains, will cool down morequickly than in the valley. This will causethe air in contact with the peaks to cool, andowing to its increase in density and that it isheavier than the air below, it will roll downthe hillside and force the warm air in thevalley up into the atmosphere (see Fig. 29).

Anabatie WindsThis wind is the converse of the katabatic

and occurs during theearlier part of a hotday.

Normally the hilltop will heat up morequickly than theground in the valleys.Thus the warmer andlighter air will rise andthis air will bereplaced by the colderair in the valley,which will have theeffect of a movementof a mass of air, oranabatic wind, up theside of the hill ormountain, Fig. 3o.

Sea and Land BreezesAnyone who has walked along the seashore

on even the hottest day will have observedthat there is usually a marked breeze (seabreeze) blowing inland, particularly duringthe morning.

He will have observed also, that as eveningapproaches the breeze will stop, but at nightthe breeze will have changed direction fromthat of the day and will now be blowing out tosea. The latter is termed a land breeze.

When the rays from the sun heat up theland it will soon possess a higher temperature

than the sea. The air in contact with thesurface of the ground will then warm up ancli'being lighter, will rise. The colder air, thatis, the air from the sea, will then blow over theshore in order to replace the rising warm air(Fig. 31). The velocity of this day sea breezerarely exceeds to -15 miles per hour, extendsonly a few miles inland, and above an altitudeof r,000ft. has no effect.

At places on the equator the day sea breezeoften exceeds a velocity of 3o miles per hour,extends up to an altitude of several thousandfeet and goes far inland. This is due to themuch higher temperature of the land nearthe equator.

At night, when the ground rapidly coolsto a temperature lower than that of the sea;the cooler air over, land will move over thesea to replace the comparatively warmer risingsea air (Fig. 32).

This night land breeze continues throughoutthe night until the land again rises intemperature.

Land and sea breezes must always beconsidered as local winds which are noticeableduring calm weather. At other times whenthe general winds, caused by pressuredistribution, are strong, the local' wind forceewill be overcome and therefore will bscancelled out.

Items of InterestElectrically driven TorpedoTHE electrically driven torpedo used with

so much success by American sub-marines in the Pacific, was developed by theWestinghouse Electric Corporation, of Pitts-burgh, U.S.A. By means of special heat -resisting materials and insulation, a motorwas developed weighing only a few poundsper horsepower. This, in conjunction with ahigh -capacity Exide battery, solved thelightweight power plant problem, and madethe torpedo possible.

The motor and battery compartment couldnot be ventilated, as this would have createda tell -tale wake. This provided severaldifficult problems, the first being that thepowerful motor produced heat intense enoughto melt the ordinary solder used to bind thearmature coils to the commutator. This wassolved by brazing the coils in place. Anotherproblem was that gases generated in the closedbody of the torpedo could have damaged theunit. Here the answer was to insert afilament -like wire in the battery-compartmentiwhich when heated burned off the gases asthey were generated.

Radar.controlled ShipSEA history was made last month when

H.M.S. Pollux, an Admiralty researchship, was navigated through the crowdedshipping lane of the Thames Estuary entirelyby radar. The officers moved away from -thecompass, the echo -sounder was switched off,and even the bridge was deserted. Discoveriesby British scientists investigating the future ofradar navigation in merchant ships made theachievement possible.

The first discovery was the chart comparisonunit which, aligned against the screen of theradar set, gives the position of the ship on thechart at a glance. The second was thedevelopment of a new type of reflector to befitted to buoys to increase their radar response.These reflectors increase the range at whichthe buoys can be detected from two to tenmiles, and the patterns in which they were laid

stood 'out sharply on the screen, contrastingsharply against the illuminated dots whichrepresented ships.

New Short Sunderland Flying -boatONE of the first results of Britain's post-war

export drive was shown on November tstwhen the " Argentina ", first of four ShortSunderland civil flying -boats for theirpassenger service in South America, waslaunched at Belfast, Northern Ireland.

From Poole, Britain's present flying -boatterminal, these aircraft-the second of whichis to be named " Uruguay "-will fly to theArgentine with British crews, under the careof the famous Atlantic pilot, Air CommodorePowell.

The route taken, incidentally, showing theflag of British enterprise, will be via Lisbon,Gibraltar, Bathurst, Natal, Rio de Janeiro toMontevideo. These flying -boats will bringto the extensive air -lines of the Argentine the

(To be continued)

performance and reliability which the militaryversion of the Short Sunderland has madeworld famous.

They are equipped to carry 4o passengersin comfort. On the upper deck a con-venient bar, in polished wood, for lightrefreshments is included, with seating for afurther five passengers when operating on

routes. In addition, r,000lb. of freightmay be carried.

With a range of over 2,000 miles at a speedof approximately 175 miles per hour and anall -up -weight of 59,000lb., these aircraft withtheir handsome lines and smartly -faired noseand tail, are a credit to British flying -boatdesign and construction-a sphere in whichthis country and particularly Short Brothershas always led the world.

OUR COVER SUBJECTTHE illustration on the cover of this issue

shows the new air liner " Tudor II"in course of construction. This machine isone of 79 similar aeroplanes which Messrs.A. V. Roe are building for Commonwealthand South American routes. With a wingspan of 12oft., and weighing 34 tons, the airliner will be equipped with a kitchen, andsleeping accommodation for 60 passengers.

The flying -boat " Argentina " entering the water after the launching ceremony


New Petter EnginesParticulars of the New Twin- andSingle -cylinder Air-cooled Engines

Two compact self-contained power plantshave recently been placed on themarket by Messrs. Petters, Ltd.; of

Loughborough. One is a twin -cylinder engine,the other a single -cylinder unit.

The new twin -cylinder engine has beendeveloped after extensive research andexperiment in the Petter works, and is nowready to take its place in the many fields ofindustry and agriculture. The provedreliability of the earlier types led to theiradoption for every kind of duty with themany Government and Service departments.The new twin Petter is of sturdy design, butachieves a degree of compactness not yetattained in any other engine of similar powerand speed, thus giving ease of portabilitywhen required. These engines are normallysupplied to operate on petrol, but withcertain modifications made at the works theyare adapted to operate with equal satisfactionon paraffin. High octane fuel may also beused as the engines are virtually lead -proof.In certain territories fuel consisting of amixture of petrol and gas oil gives goodresults. Details of such fuel and its correctmixture can be obtained from the technicaldepartment at the works.

The steady running of the engine is securedby the close co-ordination of the sensitivegovernor and the heavy flywheel. One ofthe many salient features of the new twin isthe provision of a half -speed shaft thateliminates the necessity of external gearing.,The main shaft drive can be taken fromeither end of the engine, and the shafts aresufficiently rigid to carry short belt or chaindrives of all types.

The power developed is 8 and to b.h.p.at 1,500 and 1,800 r.p.m. respectively for theis -hour rating according to B.S. specificationfor carburettor -type engines.. In accordancewith this specification the engine will developan overload of to per cent. above thesefigures for one hour, and there is an adequatereserve of power above this. The b.m.e.p.

at the 12 -hourrating varies from73 to 76.5 IIDS.per sq.in. over the range.The piston diameterand stroke are 85mm. and 82.5 mm.(about 3tin. ;: 31in.).

Cam -operatedSide ValvesThe engine is of

the 4 -stroke air-cooled type with sidevalves operated by acamshaft driven by atrain of gears, thelatter being designedto serve a half -speedshaft drive when re-quired.

The lubrication isby splash from dip-pers fitted on to theconnecting rodswhich dip into theoil sump. The splasheffect is augmented by a lubricating oil pumpof the plunger type which delivers oil tothe main and large end bearings of theconnecting rod. The oil sump has a capacityof 121 pints.

The crank pins are set at 180 deg., whicharrangement and order of firing providesexcellent balance and good carburation.

Cooling of the engine is effected by meansof a flywheel fan of the centrifugal type, withan aerodynamically designed volute and fancasing: even distribution of the cooling air isthus assured under all conditions.

Sensitive GoverningSensitive governing is an important feature.

A hand speeder control permits a speedadjustment of 15 to 20 per cent. above andbelow the rated speed. The governor is

Milling crankcase castings of the twin -cylinder Petter air-cooled engine at the Petter factoryat Loughborough.

Three-quarter front view of the new Petter air-cooled twin -cylinderengine, showing the two silencers, carburettor, and the cylinder head

exit vent for the turbo air-cooling.

connected to the throttle of the Zenithcarburettor, this, in conjunction with theWico-Pacy impulse starter magneto andLodge B.14 plugs, ensures good starting.

The engine is suitable for many diverseapplications. A new feature is the provisionOf a half -speed shaft, thus eliminating thenecessity for an external reduction gear. Bya simple operation involving the use of onespanner only the shaft extension may bechanged so that an engine speed drive can beprovided at the end of the engine remotefrom the flywheel.

The engine is suitable for electric generatingof either direct or alternating current, andwhere very close voltage regulation or especiallylow cyclic irregularity is required, a heavy fly-wheel can be supplied as an extra. This maybe desirable on heavy duty or irregular drivessuch as reciprocating pumps, etc.

The engine can be adapted for light tractionand marine propulsion, in which case suitablegearboxes or other forms of transmission willbe required about which Messrs. Petters willbe glad to advise.

Single -cylinder Air-cooled EngineThis engine has been produced as a

complement to the twin -cylinder model,with which a large number of the parts tothe extent of over 90 per cent. are inter-changeable throughout the range, includingimportant components such as cylinders,valves, springs, pistons, connecting rods,bearings, governor, etc.

The power developed is 11 to 5 b.h.p.at 750 to 2,000 r.p.m. respectively for thei2 -hour rating for carburettor -type engines.

The engine is of the 4 -stroke air-cooledtype, with side valves operated by a camshaftdriven by a train of gears, the latter beingdesigned to serve a half -speed shaft drivewhen required.

Lubrication is by the splash method, asin the twin -cylinder model. The oil sumphas a capacity of 6,1; pints. Ignition is b ymeans of a Wico-Pacy H.T. magnetowith an impulse starter-this facilitates coldstarting and reduces the effort which isnecessary for turning by hand to start up.

Cooling of the engine is effected by thesame method adopted with the twin -cylinderengine.


The Foundations of Thermodynamics-5Entropy : The Gravity and Reversible Cycle

IN the previous articles in this series thedevelopment of the subject of thermo-dynamics has been outlined up to the

point where the work of William Thomsonand Rudolf Clausius, in the middle of thelast century, produced a proof of Carnot'sprinciple which made this celebrated heattheorem consistent with the first law ofthermodynamics. It has been seen that as aconsequence of this union of ideas thereemerged a further fundamental heat theoremwhich was to be described at a slightly laterdate as the second law of thermodynamics.For some years afterwards both Thomson

Gravitational Level htMassM

Gravitational Level hz

Weight

OutputOf

Energy

Fig. 20.-Diagram illustrating the action of agravity engine.

and Clausius continued their independentinquiries into the principles of thermordynamics, but in somewhat different direc-tions. Thomson's researches led him to theconception of the absolute thermodynamicscale of temperature (1848), and to atediscovery of the thermoelectric effect (1855),which is named after him, and in 1854Clausius made the discovery of a thermalproperty of matter, afterwards called

entropy," which has since assumed a roleof considerable importance in pure andapplied thermodynamics.

EntropyWhen a stream of water passes over a

mill -wheel to generate mechanical power inthe shaft of the wheel, no water is necessarilylost or consumed as it makes its descentthrough the earth's gravitational field. Thesame mass of water leaves the highergravitational level in a given interval of timeas runs into the lower level at the end of thefall. When a stream of electric charge flowsin an electric motor from a high electricallevel to a lower one in the presence of amagnetic field, no charge is necessarily lostor transformed in the process of generatingmechanical power. But when heat is passedthrough a heat engine from a high temperatureto a lower one, some fraction of the thermalstream necessarily goes out of existence, andin the ideal case the amount of heat whichdisappears is the energy equivalent of themechanical work delivered by the engineduring the performance of a cycle. Allforms of idealised gravity engine and electricmotor possess this property in common, thatthe quantity of energy -producing agentremains conserved in amount as it falls throughthe difference in levels. By this standard,heat occupies a unique position as a source ofmechanical power, and this special peculiaritycaused Clausius to seek for some propertyof the ideal heat engine which would make itconform to the conservation law obeyed byother forms of engine. His search began withthe question, " is there, in the ideal heatengine, and in spite of the inevitable disappear-ance of some of the heat, any other thermal

By R. L. MAUGHAN, M.Sc., F.Inst.P.(Continued from page 172, February issue.)

quantity hitherto unnoticed which doesremain the same at the high and low tem-perature levels ? ", and ended in 1854 whenhe discovered such a quantity and gave itthe name of " entropy."

Gravity EngineThe approach made by Clausius to the

solution of this problem is illustrated dia-gramatically in Figs. zo, and 21. Fig. zorepresents the action of a gravity engine inwhich a quantity of matter of mass M islowered through a difference of level hl -h,(where these heights are measured from somestandard level), in a region of space wherethe gravitational field is uniformly intensewith an acceleration of free fall denoted by aconstant g. In the operation of the engine,the weight M.g of the mass moves through avertical distance h, -h,, and in so doing deliversa quantity of mechanical work given byE= M.g. (hl -h,) (I).Fig. 2! illustrates the action of the idealheat engine working in a forward cycle. Anoutput of work W is made by the engine byabsorbing Q1 units of heat isothermally andreversibly at the higher temperature T1 andreturning Q, units isothermally and reversiblyat the lower temperature T,, the work Wbeing equal to the heat balance Q -Q2-

ofapplication first law

of thermodynamics to the processes ofisothermal and adiabatic expansion of an

Absolute Temperature T1

lbsolute Temperature T2

Fig. 21.-Diagram of heat engine action.ideal gas enables the efficiency of the engine'sperformance (Qt -Q2)/Q, to be expressed interms of absolute temperatures as (T1 -T,)'T,.From the equation (Q1 (T1-T,);T1,two other equations follow at once, namely

Qiiri =Q2/1.2 and Q,-(22=Q1. (T1-T2).These combine with the equation W =Q, - Q,to give the result

W =Q1 (T -T )=Q2 (1' -1' (2)

A comparison of formulae (I) and (2)shows that just as the weight M.g of thelowered mass is the same at the high and lowgravitational levels in the gravity engine, sois the thermal quantity Q, T the same invalue at the high and low temperatures inthe ideal reversible heat engine. In his originalexposition of the theorem, Clausius gave thename " Verwandlungsinhalt " (literally" transformation -content ") to the quantityQ; T, and it is considered probable that hedescribed it in this manner since it appearedas a quantity which preserved its content inthe process whereby an engine transformedheat into work. Later he changed the name

to " Entropie " (which translates directlyinto English as " entropy "), a word whichhe coined from two Greek stems meaning" turning into," and which has a form morein keeping with the companion word " energy"which appears so frequently in the literatureof thermodynamics."Heat -weight"

Clausius was responsible for many of thereforms in the nomenclature of thermo-dynamic terms. He was the first to describethe nomenclature of thermodynamic terms.He was the first to describe the Joule principleand the outcome of its union with Carnot'sprinciple as the first and second laws of thermo-dynamics, and he introduced the adjective" adiabatic " (built from three Greek stemsmeaning " no passing through ") to describethe changes in a system which is preventedfrom giving out or taking in heat whilethe change is in progress. At a later date,Professor Zeuner employed the word " heat -weight" to describe the quantity QT, atitle suggested by the correspondence betweenthe weight term M.g in the gravity engineformula E -M.g. (h, -h,), and Q T in theheat engine formula W . (T1-T2).

The above definition of an entropy changehas been made with reference to the trans-action of a finite amount of heat Q at a constantabsolute temperature T. It can readily beextended so as to include changes in whichthe temperature of a substance is varyingcontinuously. The physical state of a body,as determined by its instantaneous values ofpressure, volume and temperature, can berepresented in the conventional manner by apoint in the plane of a pressure -volume dia-gram, and a succession of changes in whichpressure, volume and temperature are allvarying simultaneously, by a continuous, lineon the P -V diagram, as represented by ABin Fig. 22. If this line is intersected by asuccession of small but finite isothermals andadiabatics, each successive pair forming, soto speak, two adjacent sides of a minuteCarnot cycle of work, then the entropy changetransacted along any one of the isothermalsmay be denoted by dQ, T, where dQ is thesmall but finite quantity of heat exchangedreversibly and isothermally at the absolutetemperature T. The entropy change alongevery adiabatic line is zero, since the heattransacted is zero and the change is performedreversibly. The total entropy change involvedin passing from A to B along the irregularcourse of intersecting isothermals andadiabatics is therefore a sum of terms repre-sented by EaliT from A to B. As thelengths of these isothermals and adiabaticsshorten, they approach a limiting value whichcoincides with the continuous curve AB,and at this limit the total entropy change is

Volume

Fig. 22.-Pressure, volume and temperaturediagram.


represented by the conventional symbols as

an integraldQT

If the Clausius description of entropy asa ratio of a quantity of heat to the absolutetemperature at which the heat is reversiblyand isothermally absorbed or given out by asubstance is accepted as a definition, furtherproperties and characteristics of entropy canbe at once deduced by taking this definitionas a basis. An obvious property which followsfrom it is that the entropy of a substance isdirectly proportional to the mass of thesubstance, since the quantity of heat which abody abstracts or rejects to maintain a givencondition of temperature depends upon thebody's mass. Consequently, the entropy of asystem of bodies is the total sum of theentropies of the individual bodies. Anotherproperty of deeper significance which emergesis that the entropy of a substance is a thermalquantity whose value is a function of theinstantaneous state of the substance, and isindependent of the previous history of thesubstance. This amounts to saying that ifthe state of a given body is represented by apoint on the pressure -volume diagram, adefinite amount of entropy is associated withevery point in the plane of the diagram, andthat the change in entropy which the bodyexperiences as it passes from one state toanother is calculated from the differencebetween the entropy values associated withthe end and initial states, and is quite inde-pendent of the particular process whereby thebody changes its state.. Thus, with referenceto Fig. 23, if the points A and C representtwo different physical states of a given mass ofsubstance, the entropy change involved inpassing from state A to state C is the same forevery possible path which may be constructedbetween these two points, whether the pathrepresents a reversible or an irreversibleprocess. This fact can be expressed moreconcisely in mathematical terms by sayingthat the small change in entropy incurred inpassing from one state to a closely neighbouringstate is a complete or exact differential,and a graphical proof of it may be sketchedwith the aid of Fig. 23.

`, ss

s

`, `, \--`,

's'

0014one

Fig. 24.-Diagram indicating reversible cycle ofstates.

Any closed loop constructed on a pressure -volume diagram to represent a thermo-dynamically reversible cycle of states can beconsidered as the limiting position reachedby the extremities of a number of Carnotcycles drawn across the loop so as to occupyits area completely, when the number ofCarnot cycles is increased indefinitely (seeFig. 24). Each pair of adjacent Carnot cyclesin this system possess one adiabatic line incommon, and if each of these cycles is per-formed in a clockwise direction, the neteffect, if their number is sufficiently great, isthe same as would be obtained by outlining apath in a clockwise direction along theisothermals only. The entropy change in eachCarnot cycle is, by the Clausius theorem, zero,since the ratio Q!T has the same magnitudeat the high and low temperatures in any onecycle, and their algebraic sum Q, -Q272is nought. The total entropy changed summed

over all the component cycles is thereforezero, and thus for any reversible cycle the

integral -TdQ -.0. (The circle drawn through

the sign of integration indicates that thecalculation is made for a complete cycle ofstates.) If this fact is applied to any arbitraryreversible cycle ABCD, drawn so as to includean initial state A and an end state C (seeFig. 23), it follows that :

AU

But

hence

or

QT- (via ABC) + via CDA)=0

Volume

Fig. 23.-Pressure, volume curve.

A wo

dQ (via dQ1-- CDA) - (via ADC)

dQ dQ(via ABC) (via ADC) =0

dQ(via ABC) =

A

-dQ (via ADC)A

Thus the entropy change, as defined by thequotient of heat and temperature, made by agiven mass of material in passing from onestate to another, is the same for all pathsbetween the two states, since ABC, ADC are,by hypothesis, any two arbitrarily drawnreversible paths. This implies that the entropyof a substance is determined completely by itsinstantaneous state, and is independent of thenature of the process which takes it to that state.

It is to he remarked that this result isestablished by virtue of the fact that anentropy change can be calculated from the

integral) dQ only when the change of state

is made in a thermodynamically reversiblemanner. If the change from A to C weremade along an irreversible course, the entropychange would have exactly the same value asbefore, but it would no longer be equal to the

f dQvalue of the integral --.

In general terms

A

when a substance completes a closed cycle ofchanges in an irreversible manner, its totalentropy change is zero, as it is in the case ofthe reversible cycle, since the substance returnsto its initial state, but the value of the integral

Q , calculated for the irreversible cycle, is

negative, and no longer represents the entropychange. If a substance passes in an irre-versible manner from one state A to another Cwithout completing a cycle of work, its entropychange is still So S. (where S denotesentropy) as it is for the reversible change from

A to C, but the value of the integral - forf dQ

the irreversible path is no longer equal to theentropy change, but has a value less thanSe - SA. These two propositions are some-times referred to as the " inequalities ofClausius," and are formally stated as :

dQ < 0, for an irreversible cycle,

dQ <S' - S,, for an irreversible change.

Reversible CycleThey can be proved by considering the

properties of a Carnot cycle, which is first ofall performed reversibly, and then irreversibly.In Fig. 25 the reversible cycle is shown asABCD, and the irreversible one as A'B'C'D'.The isothermal line AB represents theabsolute temperature Ti of both the sourceof heat and of the engine's working substancewhen in contact with the source, since in theidealised reversible engine no temperature

- difference need be applied across the materialseparating source and working substance topromote a heat flow, as this material isconsidered to be too per cent. thermallyconducting. Similarly CD is the line ofconstant temperature T2 of the heat sinkand of the working substance when the latteris in thermal communication with the sink.One way of introducing the quality ofirreversibility into such an engine is toreplace the ideal thermal conductors by realconductors, which require the maintenance ofa finite temperature difference across theirextremities to cause heat to flow through them.In this case AB is still the constant tempera-ture line T, of the working substance in thecylinder of the engine, but A'B' is the isother-mal of the heat source at a slightly highertemperature T,'. During the isothermalcompression stage of the cycle, the tempera-ture T2 of the working substance exceedsthat of the sink T2' by a finite amount, inorder to cause heat to flow from cylinder tosink.

The Clausius theorem, applied to thereversible cycle, states that Q, IT, -Q2'T2=0.It follows that for the irreversible cycleQ, 0, since T,' is greater thanT and T,' is less than T,. If the principleof Carnot is extended to any general cycle bydividing the latter into a system of smallCarnot cycles (as in Fig. 24), and proceedingto the limiting case, the above inequalitybecomes

y TdQ

N

ti

First inequality ofClausius.

VolumeFig. 25.-Diagram indicating reversible and

irreversible cycles.

where T refers to the temperature of theheat reservoir supplying or receiving heat.The second proposition may be establishedby considering the performance of a cycle(see Fig. 25), in which the stage ABC isconveyed irreversibly, and the return stageCDA reversibly. Since a part of this cycle isirreversible, the character of the cycle as awhole is irreversible, and therefore from thefirst inequality of Clausius.

March, 1946 NEWNES PRACTICAL MECHANICS 219j,o s A

dTQ(irvrieavei6s3iL)ly) dQ(reversibly'v,,,....I T \ via CDA/"."'"

But

aRs

dQ ( reversibly \T \ via CDA ) =Sa -S., where S

denotes entropy, since entropy is evaluatedby a heat -temperature ratio when` the processis reversible. Hence,

fdQ (irreversiblyT \via ABC. H (SA- S.) < 0

or So - S, > dQ Second inequalityT of Clausius.

In an adiabatic change of state, no heat isallowed to leave or enter the system while the

change is in progress. This fact reduces tozero the integral carrying dQ in its numerator.Hence, SO- S, -0, for an adiabatic processwhich is reversible, making S, -S whereasSe- Sa> 0 for an adiabatic process whichis irreversible, making Sc> S. Thus anadiabatic change which is made in a reversiblefashion is accompanied by no change inentropy (such an adiabatic line is sometimesdescribed as an " isentropic " line), but anirreversible adiabatic process is alwaysassociated with an increase in entropy.

The fundamental relation (Q1-Q2)/Q, -(T, -T2)(1', which applies to a reversiblecycle of work, provides yet another view-point from which entropy may be considered ;a viewpoint which suggests how the conceptof entropy may be used more directly inpractical problems of heat engine design andoperation. From this equation, the quantityof heat Q2, which is returned to the low -temperature sink without being convertedinto useful work, and which may therefore

be suitably described as " unavailable energy,"

may be written as Q, T, The ratio

QaT, is the entropy acquired by the workingsubstance in drawing heat reversibly andisothermally from the source during thefirst stage of the cycle of work, and T,is the lowest temperature available to theheat engine. By this equation, therefore,the initial entropy of the working substancemay be regarded as that quantity whichwhen multiplied by the lowest absolutetemperature to which the engine has acccss,gives the amount of supplied heat whichcannot be transformed into useful work.It indicates that two desirable characteristicsin any heat engine are the choice of a workingsubstance which acquires a small entropyincrease in the process of heating, and theuse of a sink to receive the rejected heat at atemperature as low as possible.

(To he continued)

Notes and NewsFast Hammer HeadsA RECENTLY accepted application for a

patent in this country relates to a meansfor effectively fastening the head of a hammerto its handle. The contrivance consists ofa paif of wedge-shaped serrated metallickeys, and a metallic wedge made to be drivenbetween the two keys. This wedge is ser-rated on its wide faces and has its edgesconverging towards each other in the direc-tion of the thin edge of the wedge preferablyby forming grooves transversely across thefaces. Each key has transverse serrationsacross its converging faces and its outeredge.

The head of each key has a projecting lugoverhanging the outer edge of the key.

The edges of the wedge and the adjacentinner edges of the keys are shaped to effectsliding interlocking grooved and tonguedengagement with each other when the wedge

is driven between the two keys. This inven-tion should enable a hammer to keep itshead.

Watertight Flat RoofsAN inventor has been devoting his atten-

tion to houses with flat roofs. Hepoints out that flat roofs are usually providedwith a covering of asphalt or some bitumin-ous material with or without layers of feltto render them watertight.

This covering, he mentions, is whollyrelied upon to exclude rainwater. If suchcovering has any cracks or weakness, theroof may not be watertight. The coveringordinarily is black or dark in colour andtherefore is non -reflective to solar heat. Asa consequence, it provides poor insulation,and may be liable to soften or de,teriorateunder the sun's rays.

In order to protect the covering from the

Ordnance factories are now switching over part of their factory space to peace -time productionthat will eventually benefit road and civil transport. Our illustration shows mechanics busy onmotor trucks -for Europe, with the last six -pounder anti-tank gun being taken from the shed-ascene at the Royal Gun and Carriage Factory at Woolwich Arsenal. American Sherman tanks

were re -gunned in this shed during the war.

direct rays of the sun, a top layer of light-coloured material is often applied to it. Thislayer serves also to furnish a harder andmore enduring walking surface.

The aim of the new device is to providea flat roof with an entirely different kindof covering which will be waterproof andhave a light-coloured surface that will reflectthe sun's rays. In addition, it will be hardenough to carry the normal traffic on a flatroof.

The improved covering is made from twodecks, each composed of sheets of asbestos -cement or equivalent rigid material. Thesheets in the lower deck overlap one anotherat the sides and ends. They are corrugatedto form troughs, the undersides of whichhave bearing surfaces lying in a single planeand resting on the supporting frameworkor on a flat surface covering it.

The upper deck is supported by the lowerdeck, and affords umbrella -like protectionover the laps and fixing holes in the lowerdeck.

POWER FROM THERMO-ELECTRICITY(Concluded from page 208).

heat riot can in part be converted to an orderlyelectrical march every thermo-couple proves,and that the march can at least modify the riotboth the Thomson and Peletier effects prove.In the Thomson effect, a hot -point will movealong a conductor in the direction opposite tothat of a flowing current ; it might be said thatthe positive potential attracts not only thenegative. electrons but their actual high -temperature manifestations. A big step forwardwould be to prove the expected reverse to bethe case-that a moving hot -spot will evokea current.

While admitting that much experimentalwork has been undertaken in this field during.the past century, it is inconceivable that thesimple examples of its use to -day represent thelast word ; surely, the clean, simple, silentvehicles it promises, with houses and factoriesindependent of outside supply, are a sufficientinducement for more research into thisstibject so full of unsolved riddles.

REFRESHER COURSE IN MATHEMATICS

8/6 by post 6/ -From : GEORGE NEWNES LTD.

Tower House, Souttampton Street, Strand, W.C.2


Inventions of InterestParachute Pack

ONE does not require the vision of a seerto foretell that the complete conquest

of the air will soon be a fait accompli. Andthe time will arrive when every occupantof a 'plane will be equipped with an efficientparachute --that lifebelt of the aircraft.

Devoting his mind to this sine qua nonof those who travel by aircraft, an inventorhas focused his attention principally uponthe parachute pack, and chiefly to that formof pack which is strapped to the wearer'sback.

The author of an improved contrivanceof this description has aimed at a pack whichreadily accommodates itself to the shape ofthe body, so that it may be worn withincreased comfort.

One characteristic of this pack is that itsenvelope is composed either wholly or partlyof elastic fabric. Another feature is thatit has an envelope in which the directionand the degree of the elasticity of the materialare controlled to the end that, when thepack is strapped with uniform pressure tothe body, a lesser resistance to bending willprevail in that direction in which the greaterdeflection is needed.

The envelope has a bottom member withfabric side and end flaps attached. Theamount of elastic material is different cross-wise of the sheet than it is lengthwise.

Still another object aimed at is so tocontrol the elasticity of the fabric that itwill assist considerably in erecting the canopywhen released.

For Travelling CranesTHE British Patent Office has received an

application for a patent relating toelectrically propelled vehicles of the descrip-tion in which current is supplied to thevehicle from a stationary conductor (e.g., anoverhead trolley wire). This extends alongthe track of the vehicle and is traversed bya current collector (e.g., a trolley, brush, etc.)supported by and moving with the vehicle.

The invention is mainly, but not exclu-sively, concerned with electrically driven

By " DynamoI

overhead travelling cranes. It is a require-ment of certain legislation that, when aworkman is liable to be struck by a movingcrane, adequate provision shall be made forpreventing the crane from approaching closerthan a prescribed safety distance. Oneobject of the invention is to satisfy this legalobligation.

Broadly stated, the device provides safetyapparatus for automatically stopping an elec-

The inforrnation on this page is speciallysupplied to " Practical Mechanics " byMessrs. Hughes & Young, Patent Agents, of7, Stone Buildings, Lincoln's Inn, London,W.C.2, who will be pleased to send free toreaders mentioning this paper a copy of theirhandbook, " How to Patent an Invention."

trically propelled vehicle. It comprises anabutment which is secured to the stationaryconductor at a predetermined position inrelation to the track of the vehicle. And itis adapted by engagement with the currentcollector to divert the collector off the con-ductor and so break the current supply andarrest the vehicle.

More particularly the apparatus is in theform of a portable unit, comprising a shoewhich embodies a clamping device for secur-ing the shoe to the conductor at any desiredposition along it. It is arranged so as toform an abutment located in the normalpath of the current collector along the con-ductor and adapted by engagement with thecollector to throw the latter, by cam orequivalent action, off and to one side of theconductor.

Pipe Line

TN modern warfare, and possibly in peace-time, there are occasions when necessity

demands the immediate transportation ofliquids over considerable distances.

There has recently been accepted by theBritish Patent Office an application relatingto a pipe line of special construction withmeans for laying such a pipe.

The originator of this invention declares

that he has discovered by experience withexisting flexible piping that it fails underhigh pressure. Either the metallic structureleaks or collapses, or the inner rubber tubeis extruded through the seams in the outermetal covering.

The object of the improved device is apipe line which will withstand high pressureand yet be capable of flexibility sufficient toenable it to be carried in bulk as, for example,in coils of large diameter in the hold of aship.

The invention comprises a flexible rein-forced conduit which has a central cylindricaltube of ductile material. There is a cover-ing formed of one or more ribbons of hightensile strength wound spirally thereon. Asa result, the lateral edges of the adjacentconvolutions do not abut, but ate spacedand are capable of free adjustment of theirrelative positions at both the inner and outerdiametrically opposite places of the bends.

Power -operated Steering

IMPROVED steering mechanism whichhas made its advent has claimed for it

the characteristic that it reduces the manualeffort required in the steering of heavyvehicles. Another purpose is to diminishthe shock to the man at the wheel due tothe impact on the road wheels when travers-ing uneven ground.

This is a power -operated steering devicewhich includes co -axial input and outputshafts. The shafts carry arms pivotally con-nected at different points to a reaction lever.One end of the lever is movable with respectto the shafts and has a connection to controlvalve devices. The other end is connectedto the piston of a power cylinder. The rock-ing movement imparted to the lever by theoperation of the input shaft causes thelever to work one of the valve devices.Thereby power is developed in the cylinder,which reacts on the lever to balance it aboutits pivotal connection to the output armand to cause movement to be transmittedthrough the arm to the output shaft and thesteering gear.

One of the two light motor -cars to be mass-produced at Grantham by Denis Kendall, M.P. These cars are to be sold at £15o inclusive ofpurchase tax, etc. On the left is n the 7 h.p. radial engine housed in the rear of the car. The illustration on the right is a front view of

the car, showing the luggage space.


THE WORLD OF MODELSBy " MOT I LUS"

Model Railway Work in a P.O.W. Camp in Bavaria; andTHIS month sees us well through the

'winter and I hear everywhere of therevival there has been during these past

few months in peacetime model making, bothamong amateurs and commercial firms, whoare slowly but surely getting into their strideagain.

The variety of equipment offered in 5939was enormous-the result of years of buildingup stocks-and model manufacturers arestarting their post-war programme withmodels that were most in demand at theoutbreak of war ; but in the last six yearsthe taste of the model owner may havealtered, and there may be a tendency towardsmodels of more modern means of transport-as, for instance, aircraft-as opposed to ships,motor -cars and trains. An important factor,however, in the fascination of the modelaircraft hobby is that models arc onlypropelled by two methods-the simplemethod of elastic, and the small -powerpetrol engine. The drawbacks to thesemethods are that the elastic model is notmuch more than a toy, and the petrol -drivenmodel is difficult to construct satisfactorily,often gets out of control, crashes, and is atotal loss.

Model Railway Work at P.O.W. CampIt is very heartening to think of the many

model enthusiasts who carried on not onlyin this country during the war but overseas,and as prisoners of war in enemy countries.

I have already referred to several modelsmade by members of the Forces at homeand abroad, and I can now tell you a finestory of how the hobby of model railwayswas used to create interest and usefulness inStalag 383 at Hohenfels, near Nuremberg inBavaria, during many weary war years.

The story was told to me by Corporal JackGodfrey Waldron, of the Queen VictoriaRifles, who has recently been awarded theD.C.M. in recognition of gallant anddistinguished services in the defence of Calaisin 1940. He was taken prisoner at Calais andwas in German hands for five years, returningto England in May, 5945. Corporal Waldroncalled to see Mr. W. H. Rowe, of Bassett-Lcwke, Ltd., with whom he has been incommunication during his years of captivity.He told an amazing story of the develop-

ment of the modelrailway hobby so thatby the time the build-ing of the railway wasin full swing five tosix hundred men wereaiding in its construc-tion.

When taken prisonerCorporal Waldron -w h o , incidentally,lives in Northampton-was transported toPoland, where heremained in a prisoncamp there for twoyears. He was thenmoved to Stalag 383,i n Bavaria, whereconditions were betterand the prisoners wereable to think abouthobbies and had plentyof time to make plans.From the making ofcap badges, etc., theidea of toy -makinginevitably found itsway in and startedthe ball rolling forbigger things. AtChristmas -time theymade simple things andsome of the men, who

Fig. I.-(Left) Photo-graph of the new G.W.R.signal box for the gauge" 0 " clockwork line ofMr. Gilbert Thomas at

Teignmouth.Fig. 3.-(Above) A fineexample of a model20 -ton gantry crane onthe south side of theworks of the MotherwellBridge Engineering Co.,Ltd. Also to be seenare shop cranes, gantry,and special goodswagons. Scale of model,

24ft. to sin.

Some Commercial Models

were model railway hobbyists in peacetime, gottogether.

Among those in the camp was SergeantRay Beale, relative of the Rev. E. Beale, thewell-known model railway owner and writer,and Sergeant Beale suggested they shouldwrite for railway catalogues, and CorporalWaldron wrote, among others, to Bassett-Lowke, Ltd., for their catalogues and " ModelRailway Handbook."Gauge " 0 " Model Railway

The big decision was taken to try toconstruct a gauge " 0 " railway. The linesgrew from the " raw material " of emptyRed Cross tins and eventually about 48ft.of track was made, comprising four roads,crossover and switches. Electric current was

Fig. 2.-Model of the Hillman Minx (1!,0 full size) made for Rootes Group by Bassett-Lowke,Ltd., for wartime production records.


Fig. 4.-Level crossing near the main office entrance, showing gantry on the north yard and aportion of the frontage of the main workshop of the Motherwell Bridge Engineering Co., Ltd.

stepped down from 220 volts to 12 volts, andthe motor itself was made out of cocoa tins,while the wire came from such things as oldtelephone bobbins and some bare wire paintedwith shellac.

The chassis of the motor was made fromthe aluminium bottoms of the jugs issued bythe Germans (not strictly lawful but verisuccessful).

The switchboard was Corporal Waldron'sdepartment. Not having 'any isbestOs forthe switchboard, he used a piece of beaVerboarding painted over to represent asbestos.Switches and wiring were unobtainable, soknife switches were fabricated out of tin.

Fellow prisoners of war who had previouslyno model interest promptly developed intomodel enthusiasts and began listing out theitems for their railways. Smile earmarkedf50 of their post-war credits for modelrailways. On their return to England,Corporal Waldron ruefully confessed, theirhopes were dashed, for on visiting Bassett-Lowke's branch at Holborn they found thatthe firm had been on Government work thewhole of the war and none of their peacetimestock was available.

Still, better luck, boys, in the near future !

Model Signal BoxNow for the Home Front. Calling on

Gilbert Thomas at Teignmouth the otherday I was very pleased to see that he hadadded to his very attractive layout a fine new7 mm. scale model of one of the G.W.R.signal boxes near Snowhill Station,Birmingham. It is not an exact model of theactual signal box but reproduces the latestfeatures of this rather extraordinary design-the base being narrow to go between the twotracks, and the extra space required beingmade available by overhang all round (Fig. t.)

This model was made specially by Bassett-Lowke, Ltd., and the photograph shows themodel before leaving the works.

Mr. Gilbert Thomas is constantly addingto and improving his now well-known gauge" 0 " G.W.R. clockwork railway, and I heara rumour that he has written a book shortlyto be published on the origin and developmentof his model railway.

Scale Model Motor -carCommercial models are very much in

demand by firms who wish to keep a recordin tangible form of their war work, and thiseTpe'cially applies to those firms who havebeen engaged on road vehicles. In Fig. 2is shown an excellent model-t 'loth full size,of the popular Hillman Minx. This is a modelof one of the wartime productions of theRootes group, and I understand that the wholeof the series of cars and other vehicles madefor the Government during the war will berecorded to the same scale, to form apermanent record for exhibition and generaldisplay of Rootes' war effort.

Model Engineering WorksArchitectural models vary in their attraction

and detail and sometimes those which aremore spectacular from the point of view ofsize are not so difficult to make as a smallmodel which contains much mechanicaldetail. The model (Figs. 3, 4 and 5) of theengineering works of the Motherwell BridgeEngineering Co., Ltd., comes into the latterclass. The model is made to a scale of 24ft.to tin.

This has been produced recently by thearchitectural department of Bassett-Lowke,Ltd., under the direction of Mr. E. H. Clifton,and covers an area of approximately 5ft. by3ft. 6in. and is t /.88th actual size.

This is one of the best examples of a modeldemonstrating the metal working ability of themodel maker. The detail is in the machinery-cranes and gantries-and this is the work ofcraftsman J. Ashby. Besides the buildings,there are many railway sidings and tracks,and the L.M.S. main line to Glasgow isshown with a streamlined express locomotiveand train on the down track. Metal work isagain to the fore with the models of thecompany's products-container tanks,caissons, special bridge sections and so forth-made in miniature and placed in the yard,where it is usual to erect them for test beforedispatching. Another feature is the amountof rolling stock on view in the sidings-including special type wagons used by thiskind of engineering works, modelled by thescore.

Industrial ModelThis is a truly industrial model, with little

grass or trees, the ground mostly consisting ofthe company's yards. The scale of 24ft. tothe inch enables sufficient small detail to beshown with precision and is small enough, inthe case of a large works, to provide a modelof convenient size for transport and display atexhibitions. This model is now in thecompIny's offices at Motherwell.

THE SLIDE RULE MANUALBy F. J. CAMM

5/- or 5/6 by post from George Newnes, Ltd.,Tower House, Southampton Street, Strand, W.C.2

Fig. 5.-In the foreground of this picture is the L.M.S. main line with express on the down line,to Glasgow. In the background can be seen the workshop and the rear of the office buildings.


QUERIESENQUIRIESA stamped addressed envelope, three pennystamps, and the query coupon from the currentissue, which appears on back of cover, must beenclosed with every letter containing a query.Every query and drawing which is sent mustbear the name and address of the reader.Send your queries to the Editor, PRACTICALMECHANICS, Geo. Newnes, Ltd., Tower House,

Southampton Street, Strand, London, W.C.2.

Accumulator MakingT WISH to construct a special accumulator whichA involves making plates, and I would be glad ofyour advice in this matter. It is to be the standardtype of cell using the oxides of lead (PbO) yellowlead oxide and (Pb304) red lead, and I would beglad of information regarding the bindingmaterials to give the necessary strength andstiffness, and the strength of the sulphuric acidsolution required for mixing the paste.-W. H.Leyon (Coventry).THE precise methods of accumulator making are,

in these modern times, more or less trade secrets,and little information has been published concerningthese subjects.

Usually, the plate material is formed by hydrauliccompression outside the accumulator. For this purpose,up to 5 per cent. of china clay may be added to form abinder. In your case, however, you will not be ableto use this form of compression. All you can do is to" trowel " the moist paste into the plates, and to packit down in position as best you can. It is preciselyfor this 'reason that home-made accumulators are neverlong lasting, for the plate material always tends tofall away.

Regarding the acid used to make the plate pastes.This is dilute pure sulphuric acid-one part acid to4 parts water. The acid must be pure, since impureacids containing iron and arsenic will seriously inhibitthe free chemical actions within the cells.

Measuring Humidity of AirTS there any chemical material which indicatesA the amount of moisture in the air by a changeof colour and, if so, where may I obtain a supplyof such ?-Wm. D. Tattersall (Blackburn).THERE is no chemical substance which will accurately

measure the humidity of the air by means of acolour change, but there are two or three materialswhich will do so approximately.

For example, when pure copper sulphate is stronglyheated, it loses its blue colour and turns to a whitepowder. This powder, on standing in contact with theair, absorbs moisture and is gradually reconvertedinto the blue variety of copper sulphate.

Again, when cobalt chloride is heated to about720 deg. C. for a short time, the pink crystals losetheir constituent water and become blue. On exposureto the air, the blue variety of cobalt chloride rapidlyabsorbs moisture and turns pink again.

Perhaps these methods of moisture indication willserve your purpose. Copper sulphate can be obtainedfrom any druggist. Cobalt chloride is most likely to beobtained front Messrs. Towers & Co., Ltd., ChapelStreet, Salford, Lancs.

Heat Resisting GlassCAN you please supply me with the formula

for the glass known as " Oven Proof " and" Heat Resisting " or " Flame Proof " ? I havean electric muffle capable of attaining tempera-tures in excess of 1,500 degrees Centigrade. CanI produce this glass ?-K. J. Field (Erdington).IF you can readily attain a temperature of i,5oo plus

degrees Centigrade, you ought not to have muchdifficulty in making small batches of various glasses.

The various trade glasses are more or less of secretcomposition, containing specific ingredients which areonly known to their makers. However, the followingtwo formula are capable of giving heat -resisting glasses-of the type which we think you aim at :

Sand .. 60-70 per cent.Boric acid .. 15-3oPotassium carbonate.. 1-2Sodium carbonate .. . 3-6Zirconia 1-3Titanium dioxide ..

510

35

Sand or silica 70 per cent.Boric acid .. .. 16-20Litharge .. .. .. toIron oxide .. .. .. 3 ,,This latter glass is the more easily made. It is resistant

to high temperatures and to sudden temperaturechanges, and it is fairly easily worked.

Light -weight ConcreteCAN you tell me how to make light -weight or

cellular concrete using cement and sandaggregate ? I have used aluminium powder withvery poor results.

There is, I understand, a number of simple

chemicals that can be used for making this connections, andmaterial. subtract 2.

I would also like to know if it is possible to giveconcrete a high -glazed finish?-A,. J. Purcell(Dalkey).LIGHT -WEIGHT concrete is ordinarily made by

employing light weight aggregates such as blast-,furnace slags, burnt clays, pumice, coke -breeze, sawdustetc. If this aggregate contains a small amount, say,I per cent., of powdered resin, this acts as an air -entraining agent and tends to the formation of aircells within the concrete, thereby imparting extralightness to it, together with a cellular structure.

A formula which is stated to be successful for themaking of cellular and light weight concrete is :-

Portland cement part (by weight).Sand .. '-6 parts.Seed or grain husks .. 2-12 parts.Mix the above material with water to mortar con-

sistency in the usual way, so as to give sufficient fluidityfor casting.

The addition of I part of resin powder to the above,will substantially increase the amount of entrapped airin the mixture.

Concrete cannot be given a highly glazed finish, forthe reason that it is essentially porous. This appliesparticularly to the cellular concretes. You can, ofcourse, fill up the surface pores of the concrete withsize or some other material and paint or varnish overthis sealing coat, but the result will be a glazed appliedcoat, not a true glaze on the concrete itself.

Re -winding Small Electric MotorHAVE acquired the carcase of a small motorminus all windings. I wish to rewind some, and

shall be glad if you will supply the necessaryinformation.

Particulars are as follow :Commutator bars = a6Armature slots = 8Armature diameter =Armature length = zin.Number of poles - 2Voltage - 220 240 A.C.'D.C.Details of slots are as shown in the diagram.

I want the machine to run at about 5-6,000 r.p.m.-J. Devine (Brighton).THE air gap could be made about ooo6in. on each

side of the armature. Each field pole could bewound with 400 turns of 34 S.W.G. S.S.C. enamelled

t32

2

Width

rooth

Air Gap Can Be Ground To Suit

Dimensions of field magnot and armature for asmall electric motor.

"*-- /6

wile, the two field coils being connected in series so asto create poles of opposite magnetic polarity, and inseries with the armature. The armature could have8 coils, each with 220 turns of 4t S.W.G. S.S.C.enamelled wire, a loop being brought out from thecentre of each coil for connection to intermediatecommutator segments. Use a coil span from slots t to 4and so on. With the armature placed so that slots r and 4are equi-distant from the centre of one pole face,number the commutator segment which then lies underthe nearest brush, number z. All numbering is con-sidered clockwise at the commutator end.

For reversible operation connect the start of the coilin slots i and 4 to segment 1, the loop to 2, and finishof the coil to segment 3. Connect the start of the coilin slots z and 5 to segment 3, loop to 4, finish to segment5, and so on. For fixed clockwise rotation at thecommutator end with fixed brushes we suggest you addto the numbers of segments quoted above for the coil

for fixed counter -clockwise rotation

" Base -exchange" MaterialT AM constructing a water softener and would

be pleased if you could supply me with thefollowing information :

The cubic capacity of 'lb. Zelite.The number of gallons of water ilb. Zelite will

soften (approximately) as I know this depends onthe degree of hardness, and

How much salt is required to re -activate say4o1b. Zelite ?

Also, could you please inform me where I canobtain- Zelite ?-M. J. Parker (Hatfield).BY" Zelite, we presume that you refer to Zeolite

which is the " base -exchange " material used inwater -softeners.

These zeolites are made in many different forms, sothat we cannot possibly estimate the precise cubiccapacity of ilb, of the material. This depends uponthe specific gravity of the material and the grain -fineness or particle size of the mineral. Roughly speakingabout r,3rd its weight of common salt is required tore -activate a zeolite, but, as you yourself point out,the gallonage of water softened by ilb. of zeolitedepends upon the exact nature and type of the material,the speed of the water's passage through it, the tem-perature of the water, the degree of permanent hardnessof the water and the amount of surface of zeoliteexposed to the water. Since these are all variablefactors, we cannot possibly give you the figures whichyou seek.

These zeolite materials have been very stringentlycontrolled and, therefore, unobtainable by the averageindividual, but it is possible that the control may nowhave been lifted. For supplies of these zeolites writeto :-Permutit, Ltd., Gunnersbury Avenue, London,W.4. Also, write to Sofnol, Ltd., for their bookleton water softening, which may possibly bring yousome of the information which you require.

In pre-war days, many chemical supply houses usedto stock zeolite materials. Try Messrs. HarringtonBrothers, Ltd.,'4, Oliver's Yard, 53a, City Road,Finsbury Lonon, E.C.r, or Messrs. A. Gallenkamp &Co., Ltd., 17-29, Sun Street, Finsbury Square,London, E.C.2.

:Utz -steaming Preparation for SpectaclesCOULD you please inform me of a suitable

anti -steaming preparation for use onspectacles ?-N. F. Reed (Cowplain).A NTI-STEAMING preparations for glass are

usually of very simple composition, consistingmerely of various solutions of soap anchor glycerine.

A simple formula is : Rectified spirit, to parts (byvolume) ; glycerine, t part (by volume). Sincerectified spirit is expensive, you might possibly replacethe above formula by surgical spirit alone. This liquidcontains a little castor oil, so that if you wipe theglasses over with this sufficient oil may remain on thelenses to prevent steaming.

Another suitable formula is : Soap, t part (by weight) ;glycerine, t part ; water, 15 parts. Heat togetheruntil a clear solution is obtained. Wipe a little ofthis over the lenses, and then wipe it off. A minutefilm of soap will remain on the glass, which film willprevent all ordinary steaming effects.

If, of course, you work in an excessively coldatmosphere, then we are afraid that no preparationwill prevent the outside steaming of your spectaclelenses. It is a good plan to warm the spectaclesthoroughly before putting them on.

Enlargement from Cine FilmT WOULD be very much obliged if you couldA answer the following questions.

I have a roll of 9.5 mm. sine film which hasbeen processed positive (i.e. ready for projection).Is it possible for me to have a frame of this filmenlarged and made into a negative so that I canhave snapshot -sized prints made from it ? Ifso, could you recommend a firm of photographerswho would do this for me ?

Could you please explain briefly the methodused in the above operation, assuming that it ispossible ? -W. Addey (Chaddesden).IT is readily possibly for you to have a single frame

of your 9.5 mm. positive cine film enlarged so asto form a negative from which enlarged prints can bemade, and any competent photographic trade -printinghouse should be able to do this for you at a reasonableprice. Write to Messrs. Wallace Heaton and Co., Ltd.,New Bond Street, London, W.I.

Aiiiiniiiiimilmitilliniiniiiiiiiiiimilliinwilmilmmiiiiiiiiiiiiimiimmininsimimiiintimminiwiliminliiiiiiinnittnilimm

E-- ...,THE P.M. LIST OF BLUEPRINTS =="...--- The "PRACTICAL MECHANICS" £20 CAR SUPER -DURATION BIPLANE' =.,= (Designed by F. I. CAMM), Full-size blueprint, Is. =.---

.10s. 6d. per set of four sheets. The 1 -cue. TWO-STROKE PETROL ENGINE'

" PRACTICAL MECHANICS " MASTER Complete set, Is. == BATTERY CLOCK' STREAMLINED WAKEFIELD == Blueprints (2 sheets), 2s. MONOPLANE -2s.7-1 The " PRACTICAL MECHANICS" OUT- LIGHTWEIGHT DURATION MODEL

-BOARD SPEEDBOAT Full-size blueprint, 2s.= 7s. 6d. per set of three sheets. P. M. TRAILER CARAVAN' E

= A MODEL AUTOGIRO' Complete sec, 10s. 6d. E== Full-size blueprint, Is. P.M. BATTERY SLAVE CLOCK' Is. =E The above blueprints are obtainable, post free from Messrs. Ci-rge Newnes, Ltd., Tower House, =E =Southampton Street, Strand, W.C.2.fi --

An . denotes that constructional details are available, free, with the blueprint. =taw


The procedure is simple enough. Instead ofprojecting the enlarged image of your positive filmframe on to a sheet of bromide paper, the image isprojected on to a slow -emulsion plate or film. Thenecessary short exposure is given and the plate orfilm is then developed up in the ordinary way, thepositive film giving a negative image. A projectionenlarger is, of course, necessary for the work, and thetask itself is somewhat unusual, but there is nothingdifficult in it.

Small Air CompressorCAN you please help me with the following

problem ?I wish to construct a compressor for spraying

cellulose paint. For driving the compressor Ihave a one -eighth h.p. electric motor running at2,75o r.p.m. The compressor is the type used forpumping up car tyres and has a bore of anda stroke of

What gear ratio will be necessary and will abelt drive be satisfactory ?-A. H. Durrant(Basingstoke).THE suitability of your proposed compresser for

paint spraying purposes will be determined tosome extent by the actual viscosity of the paint and bythe volume of the paint material which is actually undercompression at any given time. Since your motorhas only one -eighth h.p., tiae paint container will nothave to be large, otherwise the motor will become over-loaded.

A good belt drive will be quite satisfactory providedthat the drive is not too long. Gear ratio is a vexedquestion. It all depends on the design of the paintspraying plant and, to some extent, on the power of themotor. Since we are not aware of your exact design inthe matter of this plant, we cannot give a definitefigure for a gear ratio, but we should say that a ratioof 2 or even 3 to I will be suitable, particularly with abelt drive.

Hydrogen PeroxideTS it possible to obtain pure hydrogen peroxide,A and can it be stored without the oxygenevaporating off ? What conditions must it bestored under, and where can ft be obtained ?-R. J. Bremner (Southampton).PERFECTLY pure hydrogen peroxide, which is a

thick, viscid liquid, is not yet an article of com-merce. The strongest hydrogen peroxide which isnormally obtainable is that listed as " Hydrogenperoxide 90 -too volumes." This may contain about92 per cent. of the peroxide. It must be stored in amberbottles in a cool, dark place, but, apart from theseordinary precautions, there are no special restrictionsto observe in connection with it. If the peroxide remainsuncontaminated it will keep in good condition formonths under the above conditions.

The above grade of hydrogen peroxide is obtainablefrom chemical suppliers as, for example, The BritishDrughouses, Ltd.,Graham Street, City Road, London,Ni.,. or from essrs. Harrington Bros., Ltd., 4,Oliver's Yard, 53a, City Road, Finsbury, London,E.C.r. Its price is about 6d. per oz. It is possible thatyou may be able to obtain this material to order fromyour local branch of Boots, the Chemists.

Sprayed Paper Finish on Metal SurfacesCOULD you supply any information concerning

the spraying of adhesive, followed by paperparticles, on to sheet metal surfaces (steel -aluminium alloys) ? What I have in mind is of asimilar nature to that employed on shipboard,where cork particles are used to counteract theeffects of condensation.

Could you give any advice regarding the possi-bilities of this process, together with the names offirms likely to help regarding plant, material,etc. ?-W. B. McCulloch (Alloa).SO far as we have been able to ascertain, the coating

of surfaces with paper particles (" paper dust ")has not been altogether satisfactory, mainly in conse-quence of the hydroscopic nature of the paper, thepaper attracting moisture to itself with consequentdeterioration of its under support. However, nothinghas been published on this subject, so that if yourequire detailed information it will be necessary foryou to apply to some trade or research association,such as the Paper -Makers Association of Great Britainand Ireland, Shell-Mex House, Strand, London, W.C.z.These people will also put you in touch with a suitablesupplier of paper material for your purpose.

The adhesive employed for the paper spraying is anordinary fish glue which has been plasticised eitherwith a little glycerine or with a small quantity of urea,and which contains, also, a small quantity of fine resin.The composition of this adhesive has not been published.Nevertheless, it is prepared along the above -mentioned lines. Cork particles are usually cementedto a bituminised surface, but this process is not generallyapplicable with paper in view of the staining powerof the bitumen or bitumen solution. It is essentialthat the base metal surface must be perfectly clean andfree from grease, otherwise the cement will not adherewell.

Spraying plant of various types can be obtained fromthe following firms : Messrs. A. C. Wells and Co.,Ltd., 43, Carnarvon Street, Cheetham, Manchester, 4;Messrs. Drake and Fletcher, Ltd., Kentish EngineeringWorks, Maidstone, Kent ; Hoklyhem, Ltd., HockleyHill, Birmingham, 18.

Our personal opinion of the process you mention isthat, for specialised cases, it may give excellent results,but for general large-scale use its possibilities are notvery high in view of the lack of permanence of thepayer coating.

ilfains Transformer DetailsMY electricity supply is 25o volts A.G. 5o cycles,

and I wish to build transformers havingthe outputs : A, 24 volts 4 amps. ; B, 14 volts2 amps.

Where can I obtain the iron stampings for thecores, and how is the area of the iron calculated ?

What gauge, type of insulation and number ofturns of wire will be needed for each of the coils,and can you please give any hints on carrying outthis work ?

Is there any reference book which deals withsmall transformers ?-J. M. (Blairgowrie) Douglas.THE following formula for the cross-sectional area

of transformer cores gives quite a liberal rating :

A W5.58

where A is the cross-sectional area in square inchesand W is the volt -amp. output. Hence for the 24 volt4 amp. transformer you could use a core of approximately1.76 sq. in., and for the 14 volt 2 amp. transformer acore of 0.95 sq. in. Stampings of transformer steel0.0 x4in. thick and lightly insulated on one sidecould be used, these being made to the dimensionsgiven in the diagrams. You may be able to obtainsuch stampings from Mews. George L. Scott and

'

Transformer A 24 Volts Transformer B /4 VoltsBuild Up' Core To 1.4" Thick. Build Up Core To I' Thick,

Details of transformer stampings.

Co., Ltd., of Hawarden Bridge Steelworks, Shotton,Chester.

For the primary of transformer A we suggest 1,o8oturns of 25 or 26 S.W.G. enamelled wire and for thesecondary Ito turns of 16 S.W.G. D.S.C. Fortransformer B we suggest 1,900 turns of 33 S.W.G.with 112 turns of 18 S.W.G. D.S.C. wire for the

Having obtained a suitable bobbin, through whichthe centre limb of the stampings will afterwards bethreaded, this should first be wound with the primarycoil, a layer of thin paper being wound on after eachlayer of enamelled wire. After insulating the primaryWith empire tape the secondary is wound on the top.When assembling the stampings the insulated sideof each should face the same way, the stampings beingpacked as tightly as possible, and adjacent layers ofstampings turned round so the joints in one layer arecovered by the next layer. The book " Practical Designof Small Motors and Transformers," by E. Molloy(Geo. Newnes and Co., Ltd.), would no doubt be ofassistance to you.

Telescope Lenses : Books on OpticsIHAVE a small telescope (not very powerful)A and three other lenses, all convex, from

to Sin. diameter. I am wondering if by usingthe latter I can improve the power of the telescope.I do not know the focal length of the lenses.

I would like to learn more about this subject,reflection and refraction, etc., of light. Couldyou suggest books which would help me in thisdirection ?-R. Lawson (Huddersfield).SIMPLY speaking, an ordinary telescope may be

said to consist of two optical parts, viz. : the light" collector," which is the big lens at the " end " ofthe telescope barrel, and the object magnifier, which isthe smaller eyepiece lens of the instrument. Thelarger the collecting lens of the telescope the more theinstrument will be able to " penetrate " distance,whilst the greater the power of the eyepiece, the greaterwill be the degree of magnification of the receivedimage.

Unfortunately, from your point of view, as youincrease the diameter of the light -collecting lens, youalso increase its focal length, that is to say the distancefrom this lens at which it forms an image to be magnifiedby the eyepiece lens. Consequently, the greater thediameter of your collecting lens, the longer will haveto be your telescope barrel.

You can make an approximate estimate of the focallength 'of a telescope lens by holding it in the sun'srays and by measuring the exact distance which inter-venes between the lens and the sharply -outlinedluminous disc (really an image of the sun) which thelens forms on a wall or on the floor.

A book on this subject which would interest you is :

J. Stockley, " Stars and Telescopes " (1936) (ros. 6d.),but it appears to us that you require a more generalwork on light and optics, such as :

J. Valasek, " Elements of Optics " (1928) (res.) ;B. K. Johnson, " Practical Optics for Laboratory

and Workshop " (t2s. 6d.)'B. K. Johnson, " Lecture Experiments in Optics "

(8s. 6d.).Almost any good up-to-date book on the subject of

light and/or optical instruments would fulfil yourreouirements more or less admirably.

The figures given in brackets in connection with theabove mentioned volumes represent their pre-warnet prices.

Gut ReviverT HAVE a pair of tennis racquets, which are in

need of ' gut reviver." As this is at presentunobtainable in this district, I should be muchobliged if you would tell me the substancesrequired and the method whereby I could preparea small quantity of this substance.-G. R. Perry(King's Stanley).ORDINARY shellac dissolved to a fairly thick solution

in methylated spirit is sometimes used as a gutreviver and stiffener, as is, also, a solution of gumdammar in spirit.

The following preparation, however, is stated byBennett's " Chemical Formulary " (Chapman & HallLtd.) to give much better results than solutions ofshellac, dammar, or varnish :

Boil of starch in 16oz. of water.Dissolve 6)oz. gum arabic in 16oz. water.Mix the two solutions and to the mixed solutions add

an equal quantity of a solution made by dissolving2 parts potassium bichromate in 98 parts of water.

The resulting solution must be kept in the dark, asits contents slowly become insoluble when exposed tobright daylight.

This solution is brushed on to the gut, which is thenexposed for an hour to sunlight.

The treatment is said to add from 25 to ioo per cent.new life to the gut, to stiffen it up and to render it dampresistant and enduring.

Oil Absorption Problem : Air FilteringMaterial

PLEASE suggest a material that will absorboil along a straight line a distance of at least

5yds. Similar to !,in. oil wick (not successful)material for filtering air as in a vacuum dustbag.

Also, can you recommend any books on rewind-ing small armatures similar to those used invacuum cleaner motors.-J. Gregory (London, N.).WE are not at all clear as to the precise conditions

under which you wish to make your experiment.However, we take it that you wish to set up a continuousoil absorption from one area to another by means of anabsorptive medium, but you do not tell us whether theoil has to ascend or descend, which is an importantpoint. Neither do you tell us the nature of the oil,which is another very essential point. We can onlysuggest, in the light of our very meagre information,that you experiment with various " lines " of hempenmaterial, soft tow, cotton wool, and ordinary wool.We take it, of course, that you do not wish to use apowder, such as aluminium oxide, which is stronglyabsorptive. In order to get good absorption, theabsorptive material must be absolutely dry before it isused.

The nature of material for filtering air depends uponthe air speed and pressure. A light gauge cloth willact as an admirable air filter when dealing with stillair, but it is quite useless under pressure conditions.

For average conditions of air current and pressures,a closely -woven cotton material would suit your. needs.This is made specially for various technical uses, and wewould direct your inquiries for this commodity toMessrs. Tootal, Broadhurst, Lee & Co., Ltd., OxfordStreet, Manchester.

For very high pressures, excessive air speeds and foroutside working, you might find fine copper gauzemore suitable and enduring. A gauze of 3oo'sstandard gauge should suit your needs in this respect.

Books on small motor and armature winding whichmight interest you are :

D. H. Braymer, " Rewinding Small Motors(16s. 6d.);

D. H. Braymer, " Armature Winding and MotorRepair " (r9s. 9d).

Braymer & Rose, " Rewinding and ConnectingAlternating Current Motors " (23s.) ;

C. G. Veinott, " Fractional Horsepower ElectricalMotors (23s.) ;

H. E. Dance, " Notes on the Induction Motor " (6s.).Figures given in brackets above are publishers'

pre-war nett prices. Possibly, some of the above worksmay be obtainable secondhand from Messrs. W. & G.Foyle, Ltd., Charing Cross Road, London, W.C.2.

Translucent Cinematograph ScreenT HAVE a 9.5 mm. cinematograph, and amA using a silver screen. I wish to obtain atransparent screen for rear projection, and wouldbe grateful if you could tell me what is used forthese screens, and if it would be pa32ible toconstruct one myself.-H. A. Durrant (Ed n )aton).MIX together 6 parts methylated spirit an.1 2 parts

di -butyl phthalate. Paint this liquid liberallyover the cloth or paper screen and then allow it to dryout slowly. The spirit will evaporate; leaving thedi -butyl phthalate behind in the fibres of the screenmaterial. This will render the screen translucent.Di -butyl phthalate is obtainable from most laboratorysuppliers, or from Messrs. A. Boake, Roberts & Co.,Ltd., Carpenters Road, Stratford, E.ra.

A solution of candle wax in castor oil has the sameeffect when rubbed over the screen, but, in this case,the screen becomes rather sticky and unpleasant tohandle.

Raw linseed oil rubbed into the screen wAl give asimilar result.

March, 1946 NEWNES PRACTICAL MECHANICS

Service

225

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HE used to rumble along, always the last one atthe tea-garden, the real lame -duck of the gang.

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March, 1946 THE CYCLIST 41 Aor

VOL. XIV

CEditor : F. J. CANN

MARCH, 1946 Nc. 289

Comments of the Month

All letters should be addressed tothe Editor, " THE CYCLIST,"qeorge Newnes, Ltd., Tower House*Southampton Street, Strand, London,

W.C.2.

Phone : Temple Bar 4363Telegrams : Newnes, Rand, London

Straight Words to StraussMR. G. H. STRAUSS, who, by a

fortuitous electoral circumstance,waltzed into the.Ministry of Transport

with his new broom, is carrying out thepolicy which permeates the present Govern-ment of tackling last things first. He wassufficiently misguided as to accept an in-vitation to a small London club whosemembers totalling forty or so, are all membersof either the N.C.U., the C.T.C., or theR.T.T.C. Mr. Strauss could not be expectedto know, we suppose, that the club concernedis merely a luncheon club and that it has noinfluential authority in the cycling world. Itseems, therefore, a great pity, when he hadto make, as he thought, a momentousannouncement about massed -start racing, thathe should have selected so flimsy and obscurea platform.

However, having enjoyed the hospitalityof the club, Mr. Strauss got up to make hisMost Important Announcement. He said thatmassed - start racing was dangerous and

be continued, although he hoped that thoseconcerned would take voluntary actionthemselves, the Ministry would be forced toconsider taking steps to put an end to thisserious menace to the public safety. Wechallenge Mr. Strauss to produce any evidencethat it is a menace or that it is dangerous.With a far greater experience and knowledgeof it than Mr. Strauss can possibly have, wesay that it is no more dangerous than timetrials. He knows perfectly well that hisMinistry cannot introduce legislation banningmassed -start without also banning time -trials.There is very little difference in these twoforms of racing, except in the methods ofstarting. There have not been any accidentsin connection with massed -start, but therehave been in connection with other forms ofracing on the road.

Usually, however, Ministers adopt Parlia-mentary language when dealing with mattersconcerning their office. When Mr. Strausswent on to describe those who take part inthese races, as " dangerous and anti -social,"he goes too far. There are many of us whothink that some politicians are anti -social,especially those who use unparliamentarylanguage. We do not think that massed-

* - starters are anti -social. Massed -start racingwill continue in spite of any opposition, justas time -trials have continued for over fiftyyears. Time -trials were considered dangerousthen, but they have continued all these yearsand proved the police wrong.

" Danger Bogey

THE bogey of danger has been promotedby that farcical body, the N.C.U., and

by its strange bed -partner, the R.T.T.C. Allsorts of forces are being brought to bear tokill this form of sport, because the N.C.U.knows full well that it is killing track racing,with which it should alone concern itself.One prominent midlander has sent a circularletter to all B.L.R.C. officials and known

riders. In it he says that he is worried,because of the intense fear that all forms ofroad sport will be outlawed by the Govern-ment if massed -start racing on the highwaycontinues. Fear, therefore, is at the bottom ofthe opposition, not fear because of a genuinedanger, but fear that their own form of sportwill suffer. He goes on to appeal to therecipients of the letters to refrain fromfurther activity.

His appeal, from the point o f view of results,has been a waste of paper and has caused not alittle amusement. However, if Mr. Strauss,like so many of the new brooms of the presentGovernment, wishes to exercise any powersfor reform, which he may possess, we suggestthere are other and more pressing roadmatters to be :considered before he endeavoursto do battle with the kelpie at the stream.

Let him take a drive down the Bath Road,for example, and observe the different systemsof lighting between the Great West Road andCranford. Let him proceed farther and driveinto the darkness of the stretch of the roadbeyond Heathrow Aerodrome. Let himendeavour to secure uniformity of streetlighting and insist that local authorities lighttheir particular section of the roads. He hasample powers to enforce this, since all thetrunk roads of the country are now adminis-tered by the M.O.T. Let him consider thequestion of road surfaces, curb heights, thecolour of road surfaces and the abolition ofroad islands, which bottle -neck the roadevery fifty yards or so and create dangerousconditions.

Let him consider, also, the abolition ofabout 8o per cent. of the traffic lights whichcreate traffic congestion, instead of keepingthe traffic fluid and apart. The more damsyou erect in a traffic stream the more will itoverflow its banks. .

Let him also bring pedestrians within thecontrol of traffic lights-and compel themto use pedestrian crossings, before he strainsat gnats and swallows camels.

We do not think that Mr. Strauss wouldhave touched upon this question of massed -start racing had he not been prompted onthe subject, but, in any case, we considerthat his views, expressed at a private luncheonshould not have been published, since itwas obvious from the smallness of thegathering that it was a private gathering, andhe may have been a little less guarded thanhe would have been at a public meeting.

If any legislative move is contemplatedmassed -start racing, at present run open andabove board, without any of the furtivesneak -thief methods of the time -trial, will bedriven into the same hole and cornermethods ; but it will continue. We challengeMr. Strauss to deny (evidence is on recordin his own department) that Mr. Noel Bakerwas compelled to admit that the only com-plaints that they had received when thecontroversy started was from the N.C.U.and the R.T.T.C. We also challenge him toproduce any evidence outside the figments

By F. J. C.

of his own imagination that massed -startracing is dangerous.

The N.C.U., we would remind Mr.Strauss, originally controlled time -trialsand attempts at records on the road, buttowards the end of the last century theybanned it as dangerous and turned theirattention to track racing only. Time -trialsand road records are now governed by twototally different bodies.

Road Accidents-December, 1945

CASUALTIES on the roads duringDecember totalled 14,o53. Deaths

numbered 533 and cases of serious injury3,226.

Compared with December, 1944, there were76 fewer fatalities, but the number of injuredincreased by 1,895.

The following is an analysis of the numberof deaths according to the type of vehicleprimarily involved :

Type of Vehicle No. of DeathsService (British, Dominion, and

Allied of the three Services)Public Service and HackneyGoodsPrivate CarsMotor CyclesPedal CyclesOthers

Total :

5o90

116154

535515

533

The term " vehicle primarily involved "means where more than one vehicle wasconcerned, the vehicle to which the accidentappeared to be primarily attributable. Inno case does it imply that the driver of thevehicle was culpable.

The Safety Campaign

WE pdloannniontgkntohwe wpuheortlies r,e,sip(oenepsibleeaftohr

Off the Roads ' advertisements, which aregoing to cost the country a cool quarter of amillion pounds, but they have the sameimbecilic touch as many of the Governmentposters had during the war. They revealan appalling lack of knowledge of the mentalityof the public, and presume that we are a lotof unintelligent schoolchildren 'who can becajoled and gently chided into mending ourways. Quite apart from their stupidity,some of them condone manslaughter andendeavour to place the blame on the otherperson for not anticipating that the driver ofa car had ineffective brakes. The scheme hasbeen running long enough for us to be able toassess its value ; it is nil, as the accidentreturns show. This Government, which hasdistinguished itself by promoting schemesfor spending money and few, if any, forproviding it, could have put that sum ofmoney to far better use in removing dangerspots from a number of our roads. Whenshall we have someone in the Governmentwho really understands the road problems ?

4

42 THE CYCLIST March, 1946

Doing WellWE are now well launchedinto 1946, and up to the

moment of writing it has not been too bad asfar as I am concerned. Physically I have managedmy full quota of riding, which has extended in milesas the light has lingered in the west, giving me an hourof easy journeying on the longer way home and thevision of the fields and woods that have been but amemory for the past weeks. How good it is to getback to the evening saunter with its refreshing changefrom the well-worn way of the direct route. That isthe value-or one of them-of being a daily cyclist,you just take the chance of an hour off in your stride,pick up your friends along the road again, and stillarrive home in time to hear the " nine o'clock," read apage of history, ancient and modern, digest the domesticnews, and supplement that need for living, a comfortablemeal. And mechanically I am lucky. My bicyclesare running with perfection and silence, and are stillairborne on pre-war tyres, a condition of comfortonly attained by guessing the shortage -to -be in theearly days of 1946. So I am not worrying about theimmediate future, being well provided with the machi-nery to take all the chances of roaming that may comemy way during this year of grace. Sometimes I marvelat my fortune in coming through the war years sohappily, and in so doing give a few moments of thank-fulness to the people who have preserved for me thislovely land, as I lean over a five -barred gate and watchthe March mad hares scampering along the shallowditches and see the last of the light quiver over thequiet mere. I am here, and I may not have been ;I am free to pursue these simple pleasures on a simplemachine that paces the land from sea to sea when thehighdays are all'' -mine, and I feel, stronger than everbefore, that this country is so much mine that I cannever appreciate it sufficiently.

The Truant Tzvicertandem has just returned home. It has been

lVk adventuring in the company of two men of theold 14th Army home from Burma. One of them wroteto me in the late summer to know if I could fix them upwith a tandem with which to tour during their long leaveand cure the nostalgia of nearly five years absence fromthe homeland. I suspect they knew of the existenceof any old machine and imagined I would fall for therequest. And I did. Who wouldn't, when you rememberwhat these lads have done for us ? They collectedit one day in the late autumn and the next I heard ofthem was at Lynmouth, from whence a long epistleof joyous adventure arrived, making me feel a triflejealous of their wanderings by way of Exmoor and thecoastline southward, where apparently they foundwelcome accommodation everywhere ; not surprisingconsidering it was then mid -November. 'They wereaway a month, partly Indian summer mixed with stormand the glory of great seas coming ashore. Then, ontheir last day, combing the ridge of the Malverns,the back axle broke (not surprising considering themachine has some 30,000 miles to its credit), so that thetrain was the only convenience left. And now, afternearly three months that specially long axle has beenreplaced, and the old twicer seems as fit as ever onceagain. In the interim my one reliable tandem partnerhas returned from the wars, so it may be that I'll bepart of the crew on numerous occasions, which willcertainly b a change after a lapse of nearly five years.EM two on tour I think a tandem is ideal, always pro-viding the crew " nick " in pedal action and are reason-ably good companions. From my youth onwards Ihave been a tandemist, for until the close of 1917,when a major operation intervened, my good lady wasmy constant companion, and she swears now that theywere the best holidays ever.

The Season ofSeasonsS far as' I have been

" concerned the wintersolstice has been anagreeable one for mypurposes. I have enjoyedsome happy journeys, notall of them in fine weather,but nevertheless happy, forthere have been brightspots in most of my outingdays. and even when it hasrained and stormed thecompany was good, and afew miles along the Madawaited tea and a jolly firewith the inconsequentchatter of merry people. Ido not think there is anyother game that can takethe . run of the elementswith such a wide philosophyas cycling and especiallycycling in company. Youcannot be gloomy orwithdrawn,, or feel that youare the sport of circum-stance ; indeed, you arerather the circumstance ofsport even when the drivenwater drips from the end ofyour nose and the windtries to tear the cape fromyour shoulders. But apartfrom these oddments of"rain spreading northward,"as the weather forecastssay, there are many beautiful

days in winter when the mistily filtered sunshinebreathes a benison on you and all the tints of wintersparkle. Tbat frosty morning under the pale blueof the sky, so quiet that the silver patterns of the cob-webs hang on the hedges like frozen breath and thelittle puddles are crinkled with thin ice ; ah ! to be outand about then is to take from the English winter oneof its greatest pleasures. And now as you read theselines we shall be looking for the footprints of Springin the sheltered hedgerows, and over the young wheatwill blow to us, as we lean on the gate and look towardsthe empurpling woodlands, the warm breath of thesouth -wester coming overseas from the spicy islesand faintly laden with their perfume. The season ofseasons is almost with us, " the horns of elfin faintlyblowing " can be heard if you listen at the edge ofsome copse over which the white clouds are sailing,trailing their shadows along a lovely land.

The Way of ItALL these things are awaiting you if you will but

seek them. The way is easy and the methodof cycling is within the reach of nearly all people ;cycling, that keeps a man active and simple and young,one with the land and all its teeming beauty. You cantake it or leave it ; there is the invitation ; and thelike of it had never been given to mankind until heinvented the bicycle. But if vou leave it for othermodes of travel, I tell you frankly you will be unwise,for you will grow older more rapidly, the inhibitionsof middle and elder age will settle in you, and thespice of life will lose much of its flavour. I bow tono man's opinion on this matter, for I've proven thetruth of it. I can, of course, understand and some-times sympathise with all the excuses as to why menfall away from cycling ; but that knowledge does notalter the fact that a mangets more. out of life bythe process of simpleactivity than by indulging afar more costly manner oftravel. I am not " upagainst " the motor-car-acharge frequently levelledat me-I am just all forcycling because it weavesthe spell of travel for memore romantically than 1"other means of movement,and possesses the all-pervading grace of activity,that easy use of the musclesflexing the body to fitness,imposing exercise uncon-sciously taken. I knowmen of my own age whoride with me seem to behappier mortals becausethey are active ones ; andI'm perfectly sure I am.However young you whoread may be, rememberthis : you have got to growolder ; but if you weregiven a pleasant method ofretaining, both mentallyand physically, the boonof a youthful outlook andthe grace of easy movement,would you take it ?here it is on offer and itcosts nothing. The worldstill has to learn these goodtidings, but because theypossess no complicationsand no ritual theunbelief, in a plain fact, is

111

/ LongWitten.harn .

rierks

line ancient marketcross of this femaletittle Village us the.111201e8 pas,

colossal. Nothing can cure old age, but regularcycling can make it younger.

You Can't OverstateHAVING written that in the full belief that it is

true, I shall probably be taken to task by some ofmy friends who will tell me I have overstated thecase. I ant getting accustomed to that type of criticism,to be dubbed a fanatic because I love a certain way oflife that has provided me with the crown of health andsurrounded me with an oriel of loveliness all the daysof my existence. And then they say to me, " I don'tknow how you do it ! " as if it were a miracle for a manof my years to be active, which, of course, is absurd.I do it because I am active, and I'm still active becauseI do it ; and so can every one of you carry the joy, ifyou will but remain loyal to the game. And what adividend it will pay you! And there I speak out ofknowledge without the aid of imagination or theemphasis of the advertiser. Of course, there is ameasure of wisdom to be used in this cycling pro-gression adown the years, and I think that definitioncan almost be given in the one word, comfort. Speed,in the racing sense, you can still enjoy by proxy if youso -desire, but every other form of cycling is at yourdisposal. My idea of comfort in these days is a widefour -wire saddle from the seat of which all comfortflows. Easy gears make easy riding, sixty for me asa normal, dropping to forty-three in the low range, andI can then average so m.p.h. on a days journey andenjoy every league of it. Most folk who ride are gearedtoo high (I am not speaking of the racing or the fastclubman) and would trundle their normal pace of tento twelve miles an hour more comfortably in sixtiesor sixty -threes, and sit easier in the saddle if theysported a slightly -dropped bar with grips level with theseat top. And I like my saddle peak level and atleast three inches behind a vertical line drawn throughthe bracket axle. These things are important to com-fort and-I regret to say it, but it is true-mainly ignoredby the average rider, and often sneered at by that typoof cyclist whose handlebars are reminiscent of theplough.

Such a ChanceIWONDER whether the railway people will under-

stand that cyclists, and especially touring cyclists,can and would be their good customers if any regardwere shown for their comfort, and the decent handlingof their property. I have long felt our rail systems lookupon the cyclist, first as a nuisance, and secondly as anindividual who has gained freedom of travel at theirexpense. If we can get by rail to our touring area quickly,reasonably, and free from the fear of damage to ourproperty, I am certain the return to the railway peoplewould be considerable. But it is most difficult topenetrate the hide -bound notion of officials thatcyclists would form any considerable part of theircustomers. Attempts have been made time and again,and the small concessions organised cycling has- beenaisle to obtain have never been sufficient to be reallyattractive, while at the back of the official mind one hasalways sensed the notion that we are not wanted-only tolerated. Towns are spreading, and will spreadmore in the next decade ; the way to the open countryfor many of us is via six miles of building canyons.Suppose we could get cheap fares, morning and eveningat the week -ends, to carry us beyond the bricks, andbring us home again at night, do you think suchconcessions would pay the rail folk ? I do ; and also Ibelieve the round ticket taking you to one area aridreturning from another would soon become exceedinglypopular and introduce a new form and type of week -endtravel. If the rail folk do not introduce some sucharrangement, I think road transport might easily stepin and obtain quite a lucrative busineSs.

Tr,

---5:1;n7f7T n

T-1:30f--1711k.t-

March, 1946 THE CYCLIST 43

Around the WheelworldNew Charlotteville President

CONGRATULATIONS to Vic Jenner,who at the recent annual general

meeting of the Charlotteville C.C. waselected president of the club. The formerclub captain and treasurer, who now succeedsto the highest position in the club, has beena protean worker in its interests. It is adistinction which he greatly deserves. Thevacancy occurred due to the previouspresident, Mr. E. F. Mitchell, moving toBirmingham. Vice-presidents elected at themeeting were Harry Woolgar, C. Cripps andMajor Lew Kent. D. Grey, of Rockstone,Eashing Lane, Godalming, Surrey, wasre-elected race secretary, whilst club racesecretary remains W. Stickley. The - hon.gen. sec. is D. Staerck, of 16a, BrightonRoad, Godalming, Surrey.

The Interim ReportTHE Interim Report of the Committee on

Road Safety, which has been so muchquoted, particularly the paragraph relatingto massed -start racing, is worth a littleexamination. Let us examine the terms ofreference :

" We were appointed by the Minister ofTransport in December, 1943, to report onthe matters covered by the following termsof reference. To consider and frame suchplans as are possible for reducing accidents

on the roads and for securing improvementsin the conduct of road users in the interestsof safety and to review the recommendationsof the Select Committee of the House ofLords on the Prevention of Road Accidents,and to advise on those which should beadopted as measures of post-war policy forthe reduction of accidents."

As massed -start road racing was notresponsible for any death or accident, eitherbefore or after the deliberations of theCommittee on Road Safety, it is obviousthat paragraph 115, page 37, of the Reportis entirely out of order and would seemto be an inspired statement. Moreover, thechairman of the Committee abused hispowers by permitting the subject to bediscussed, as it was outside their terms ofreference.

B.L.R.C. to be IncorporatedAT the annual general meeting of the

National Executive Committee of theBritish League of Racing Cyclists held inLeeds on Sunday, January 27th, the decisionto incorporate the League into a limitedcompany was ratified. It was decided thatthe League should be registered under thePermanent Friendly Society Act, and anappeal was made for funds to help carry on.The task of registering the League under thisAct will be completed in approximatelytwo months.

Mr. James Kain was again elected generalsecretary.s

. ' A fighting reply was made to Mr. G. R.Strauss, M.P., Minister of War Transport,in regard to a speech reported to have been

ade recently by him at a meeting of alocal club in London and it was decided tooppose and fight him all the way. Proofwas put forward to show that no increase inroad accidents was being caused by theLeague, as the insurance company had notyet been asked to pay any compensations forriders having been involved in accidents.Each rider has to pay 2s. per annum, andthis sum has not been raised by the insurancecompany as a result of accidents havingoccurred.

By ICARUS

Mr. James Kain announced that at Easterthree racing teams from Ireland would bevisiting this country. One team will takepart in the track meeting to be held atHampden Park, Scotland, before the Scottishcup final on April loth.

A second team will be riding at Paddingtonon April loth and the third will take part inthe Dover to London race to be held onEaster Monday.

On Easter Saturday the Irish riders will takethe opportunity of being in London, and areunion of the London -Irish will be heldin Town.

It was also announced that the 5 -dayVictory Marathon held during 1945 cost theLeague £600. A strong recommendation wasmade that the 6 -day, to be held on July 29thto August 3rd, 1946, should be organised by aprofessional promoter as too much work willbe involved for a part-time promoter.

Approval was made on all events drawn up.A resolution for the establishment of an

" Independent " class of rider, half -waybetween amateur and profeSsional, waspassed and the licence fee for Amateur,Independent, and Professional riders wasfixed at 2 6, to;'-, and £2, respectively.

A new rule to the affect that a log bookshould be signed by the competitors at thestart and finish of each race according tointernational practice, and another that where -ever possible all road race finishes shall takeplace on a private ground (i.e., stadium,arena, a field, etc.) was passed.

The new Handbook for 1946 will bepublished in a month's time. The registrarin his report to the executive stated that theLeague now has t,000 registered riders onits books.

Delegates to the meeting came fromscattered areas throughout:the country betweenGlasgow and Bournemouth. London wasstrongly represented.

As a result of recent elections the followingofficials have been announced to conduct thebusiness of the London Section, B.L.R.C.,for 1946 :

Chairman-W. Summers, 4c, LowerCamden, Chislehurst, Kent. General Secre-tary-P. L. Marshall, 38, Coopersale Road,London, E. 9. Assistant General Secretary-E. Lawton, 44, Lammas Park Road, Ealing,W.S. Event Organiser-A. H. Clarke, 7,Chestnut Road, Enfield, Middlesex. AssistantEvent Organiser-C. Walker, 24A, OxfordGardens, Kensington, W.to. Treasurer-V. Humphrey, 28, Haslemere Avenue, BathRoad, Hounslow. Track Secretary-S.Garrard, 9, Abbott's Crescent, HighamsPark, E.4. Press Secretary-R. Fairman,61, Chestnut Avenue, Buckhurst Hill, Essex.Social Secretary-C. Owen, I t, ChingfordMount Road, E.4.

Roadfarers' Club A.G.M.THE 3rd annual general meeting of the

Roadfarers' Club was held in Januaryand was preceded by a dinner which waspresided over by Mr. E. Coles Webb. Mr.J. Dudley Daymond took the chair at theA.G.M. The hon. sec., Mr. R. A. West,reviewed the difficulties of the past year,when V -Days and the General Election upsetplans. The club was founded in July, 1942,with a membership of ten and now has amembership of some hundreds. The club is ina sound financial position as shown by thesecretary's report. The press secretary,Mr. F. J. Camm, announced No. I of theClub journal, The Roadfarer, would shortly bepublished. Mr. Camm was elected avice-president. The press secretary,treasurer, and secretary of the Council were

re-elected with acclamation and the president,Lord Brabazon of Tara, of course, continuesto occupy the presidential chair.

Release of Service CyclesM1ANY Service bicycles which have become

surplus are to be exported, and anumber will be made available to dealers forre -sale in the home market, Mr. GeorgeWilson, O.B.E., stated in Birmingham onbeing re-elected ' president of the BritishCycle and Motor Cycle Manufacturers'Union.

During the war, he said, they had exportedi,42o,8o6 bicycles and 23,902 motor -cycles.For these and for cycle and motor -cycleparts £14,000,000 had come back to thiscountry.

Britain had made 2,500,000 bicycles forcivilians at home in the war years and suppliedthe Army with 400,000 motor -cycles.Thousands of bicycles had gone to theNavy for coastguards and others, and toR.A.F. stations for pilots and air crews toget from their quarters to their 'planes.The Dutch, who had 20,000 Service machineson order, would be using hundreds of theseR.A.F. bicycles. Liberated Europe hadreceived 20,000 new bicycles from Britainsince V -Day and it was hoped to make thetotal up to 100,000 during the year.

Mr. C. Douglas Terry, of Herbert Terryand Sons, Ltd., Redditch, was re-electedsenior vice-president and Mr. J. Y. Sangster,of Ariel Motors, Ltd., Birmingham, juniorvice-president.

Dynamo Hub ActionMR. JUSTICE VAISEY, in a recent

action, brought by the Raleigh CycleCo., Ltd., asking for an injunction restrainingMessrs. Miller and Co. from infringing theRaleigh Hub Dynamo patent, made an orderrevoking the patent. The judge agreed thatthe Raleigh Company had made out its case,but they failed on the question of the subjectmatter of the invention. He thought therewas nothing novel in the dynamo, or in placingit in the hub of the wheel. There may be anappeal.

The Supply PositionBICYCLES will be high in the list of

things which many readers would liketo get, but cannot.

The situation improves. Britain made1,600,000 units in bicycles and parts lastyear and we hope to raise the figure to5,000,000 units during 1946. If we do, andthe number there will largely depend on thenumber of men and women we can get tomake them, two out of three are alreadybooked for overseas.

How many people are aware that the worldbought more bicycles from Britain beforethe war than from all other countries puttogether ? In 1937 we sent 831,113 completemachines overseas and got £2,329,313 forthem, with £2,323,664 for cycle parts, atotal of £4,652,977. In the same year therest of the world exported 729,224 machinesfor £1,418,107 (in some cases their returnincludes bicycle parts and bare frames).

Japan with 461,951 complete machinesand frames (if one could describe any Japanesebicycle as complete) and Germany with166,864, will not be in the running for someyears to come. Even, therefore, when wereach our ultimate aim of 6,000,000 bicycleunits a year, there will be more than enoughriders clamouring for them in bothhemispheres.

44

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6y Me iouelm medievalimidqe acres, the 'Name; .

THE CYCLIST March, 1946

CYCLORAMA

A World in WhiteTHERE are people who only like to see

snow on Christmas cards, and alwaysgrumble when, awakening one morning, theyfind the familiar ground covered with a mantleof white. But there is beauty in the snow,and even though it makes " hard going " forthe cyclist, I think there is something to besaid for a ride on snowbound roads, for undersnow the countryside looks very different ;trees take on a new and ghostly beauty, andeach familiar field becomes a strange land ofwhite. And when the sun breaks through,and shines on the white landscape, then thereis loveliness indeed, and one has memories ofSwitzerland, and sunshine that almost hurts,and tinkling goat -bells, and all the glory ofwinter sports. . . .

A Kipling MemoryAGOOD cycling friend of. mine recently

took my advice and took his bike intoStaffordshire. I had told him that he mustforget the grime and smoke of the Potteries,and the ugliness of the Black Country, andset out to find the charm and beauty whichthe county holds for those who seek it. Myfriend cycled through goOd country, kept meadvised of his progress, and wrote me aninteresting letter from Rudyard-that littleplace at the end of the famed Rudyard Lake,which is a reservoir some two miles long and400 acres in extent. And the burden of hisletter was that he never knew that it wasRudyard which gave Kipling his baptismalname ! Of course, it is true, and I fanciedthat everyone knew that it was in the lovelysurroundings of 'Rudyard Lake where Lock-wood Kipling courted Alice Macdonald ;here, amid the leafy beauty, he asked her tobe his wife. When their son was born inIndia, the father and mother, with fondmemories of their courtship in the Rudyarddistrict, named the boy Rudyard . . . and sothis bit of Staffordshire has a very special linkwith the poet of Empire.

Who is Our Oldest Cycle Trader?AN interesting query-but perhaps difficult

to find the answer. Anyway, I recentlysaw some correspondence from Mr. Prentice,

fe:S.

eaf:

4

of Wickford, Essex, who was certainlymending punctures in the year 1889. Now,that was the very year in which the famouscycle race was held at the Queen's CollegeSports, Belfast, when the famous Du Crosbrothers demonstrated the advantage of thepneumatic tyre over the old solid. Goingback a bit ! But I wonder who can claim tohave been in business the longest period as acycle dealer ?

The " Charlotteville " ClubMY old and good friend, " Ed " Mitchell,

who left London for Birmingham a fewmonths ago to take up the position of DunlopMidland Regional Manager, informs me that.he has resigned from the Presidency of theCharlotteville Club, finding it impossible tofill that distinguished office when quarteredso far away. " Ed " is followed by VicJenner, too well known in cycling circles toneed any introduction. The club has lost agood and popular president, but been luckyenough to get a worthy successor-to whomgood luck and good fortune !

The " Apologies " are Nearing Their End

YES! I think that that melancholy note of

apology for no supplies, which has beensuch a familiar feature in British advertisingduring the war years, is disappearing at longlast-even from the cycle makers' announce-ments. You know the theme : " Some dayyou will again be able to buy a ' Sentinel 'Well, there seems more and more cycles in theshops, and there is a new note of optimismcreeping into the cycle manufacturers' adver-tising, at which I rejoice greatly. Speed theday when there will be no shortage-the daywhen one can make a selection, browsethrough a bulky, well -illustrated catalogue,the day when the ogre of Austerity has beenbanished for ever !

Shades of Doctor JohnsonTHE great lexicographer was much in my

mind during the Christmas holidays, forI spent the days near Ashbourne, and actuallyregaled myself with ale in that famous old inn," The Green Man and Black's Head," whereone may be shown the identical chair in whichthe Doctor used to sit and sip his ale in the

By

H. W. ELEY

long ago. There is another associationbetween ale and the Doctor, for I fancy thathe had some connection with the Barclay -Perkins brewery at Southwark, and his" head " appears on some of the bottle labelsissued by that famous old firm. Ashbourne,despite bitter winds, seemed full of cycles-but then, if you live in a small country townyou find a bike an essential possession ! Andit still remains the best and cheapest form oflocomotion, the ideal mount for man, womanand child.

Frost . . . and the Birds(THEN the land is in the iron grip of

King Frost, the garden lawn hard andrime -covered, and the ponds all frozen,then is the time for the cyclist who is a loverof bird -life to remember the birds' " foodproblems," and see to it that the bird -tablehas a goodly supply of crumbs. I almostsaid " and bits of fat," but I suppose thatunder our austerity ration scheme even suchtrifles are impossible. But crumbs . . . yes ;and it is a grand sight to watch the sparrows,the chaffinches, the robins, and the sleekblackbirds twittering and disputing for thedainties which, while the hard frost lasts,must take the place of grubs and worms.

Come to CoventryNOT for some months had I been to

Coventry and had time to ramblearound its streets. But recently I did spendsome hours there, thinking of its many tradesand manufactures over the years, deploringits sad scars due to the blitz, and musing uponthe legend of Peeping Tom, and rememberingthe good William Ford, the gracious founderof Ford's Hospital. And Peeping Tornbrought me to Lady Godiva, the wife of EarlLeofric of Mercia . . . and I recalled thatLeominster, in fair Herefordshire, wasoriginally " Leofric's Minster." But Ithought chiefly of all the famous makes ofcycles for which the City of the Three Spireshas been famous ; I remembered renownedold " brand -names " and how they hadcarried the fame of Coventry to the uttermostparts of the earth. And, in view of the vitalneed to rebuild Britain's export business, Irejoiced that Coventry still made good cycles. . . and sent them overseas to carry thebanner of British craftsmanship among thepeoples of distant lands.

It's Good to Keep a DiaryTHE New Year . . . and we put away, or

destroy, that diary which has been sncha faithful companion through the old year. . . we glance at notes we made, recall allkinds of " dates " and events, and write ournames and addresses in the new diary for1946. There is always, I think, a little thrillabout starting a new diary, and I hope thatmany of my readers make a point of recordingtheir riding experiences, noting down theirmileage, and in short keeping a " runningcommentary " of the year's cycling. It is sogood to look back on such records; I havekept them for many years, and the other night,over a final pipe before the dying fire, Iturned over the pages of a diary for the year1928. What a year of plenty ! More than onenote of " ham and egg tea " at some waysideinn or cottage ! More than one mention ofbuttered scones and jugs of cream ! Perhapsall such good things will come back duringthe course of the present year. Anyway, letus salute 1946, and hope that as it runs itscourse we shall really emerge out of theshadows of war and its aftermath, into thefull sunshine of permanent peace. Goodriding to all !


"After what I saw 'out there'no other tyre will really satisfy me now"

BEST TODAY * STILL BETTER TOMORROW

46 THE CYCLIST

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March, 1946

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rhe tutrn inthe roThe turn in the road,ever revealing theunexpected, is oneof the fascinations ofcycling. But ;t mayalso reveal an un-expected emergency:be ready to meet it.

Remember, rain or shine youcan cycle in safety if you fit

FERODOALL-WEATHER BRAKE BLOCKS

FERODO LIMITED CHAPEL -EN -LE -FRITH IFERODO1E , 0

41


Fresh StartT ANARKSHIRE Road Club lostA, nearly all its members owingto Service calls. The club is nowbeing reformed with J. Leonard,tot, Newarthill Road, Carfin,Motherwell, Glasgow, as secretary.

Watch on the RhineACYCLING club has been

formed among ofthe Rhine Army headquarters

Sibbitt's New HonourSIBBITT, famous path riderJ of the Manchester Wheelers,

has been elected president of thatclub. He follows A. J. Bradbury.

DecoratedT //CPL. W. COWELL, IlfordA -, Road Club, who is servingwith the R.A.S.C., has been awardedthe Military Medal for gallantry.

JHe was previously mentioned indispatches.

kl.Devon. r grain Six -day Race for London?""iihc5-ps Tawtot.

R.A.F. Club Disbanded . . .

(\WING to Service movements the R.A.F. Club.N-1 known as the Dunmow Road Club, which hadmany fast men in its ranks, has been disbanded.

But New One FormedA T Blibbrook, Lincs. the Blinbrook (R.A.F.) Club

which caters for airmen in the vicinity has beenestablished.

Cozens Home AgainQ YD COZENS, a Flight Lt. in the R.A.F., has been

demobbed. He was a member of the famousManchester Wheelers and rode in a number of Six -dayRaces.

Yorkshire VeteransTHE Veterans Time Trial Association has extendedA its activities to Yorkshire, where a section hasbeen formed with C. F. Bause, ii, Fellbrook Ave.,Acomb, York, as its secretary.

Activity in KentTHE Kent Cycling Association has been resuscitated

with C. R. Etherton, 163, Rochester Ave..Rochester, Kent, as hon. sec.

Old Timer DiesFORMER well-known official of the N.C.U. Devon

and Cornwall Centre, W. Eva, has died. He was86.

Champion KilledVORMER champion of the Kingston Road CyclingA- Club, J. Compton, lost his life in an airplane crashwhen on his way home from imprisonment in Japanesehands.

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Herefo*dahee.

quaint bmbe. market.and the Newlin.

TT is suggested that London will1. have a six -day race this yearat Wembley Stadium.

Down; UnderMORE cycles arc to be

permitted to be im-ported to New Zealandthis year.

No LuxuryTN France the LuxuryA Tax on cyCles has beenlifted and standard pricesfor machines have beenfixed.

The Industry MovesCYCLES are to be mann-

factored in Mont-gomeryshire by TubeInvestments, Ltd., whichis taking over a Govern-ment factory.

Now MixedTHE Crest CC., of Ilford,

Essex, have openedtheir ranks to ladies.

Road ImprovementsOVER a quarter millionsterling has beengranted for road improve-ments in Skye.

Middle East Record

A

T SMITH, Manchester Clarion C.C., is holder of theA- Middle East 25 -mile record with x.5.3. He madethe ride as a member of the Peninsula C.C.

Octogenarian PresidesGEORGE JOWITI, So -year -old president of the

Upperthorpe C.C., presided at the club's 65thanniversary celebration.

Arthur Moss, J.P.ARTHUR MOSS, Wessex Road Club, has been

appointed a J.P.

SuggestiveTN his report to Kesteven (Lincs.) Standing JointA Committee, the Chief Constable stated that cyclethefts during the, past quarter had decreased " insympathy with fewer offences attributed to membersof the Services."

Don't Do as I DoA MEMBER of a Huntingdon local authority has

been seen more than once cycling on the pave-ment. His idea is apparently that other cyclistsshould do as he says and not as he does.

Grantham Road ClubAT the annual meeting of the Grantham Road

Club it was stated that the club is now back toits pre-war position as the strongest in Lincolnshire,with an increased membership from 47 to over goduring 1945. Financially, the year was also stated tohave been a good one.

novel exhibit at the Paris Fair, held last autumn. A spring -likebicycle wheel made to meet the shortage of rubber tyres !

" Safety First" PioneerQERGEANT HARRY GILBERT HATHER, who'-' instituted special tests for child cyclists in Don-caster and designed badges for those children whopassed the tests, has died, aged 49. He had spent25 years in the Lincolnshire and Doncaster PoliceForces and had been retired on pension for less than12 months.

Gulls at ScawbyBECAUSE during the war eggs were taken in very

large quantities from the gull breeding pondsat Scala -by, Lines, there is a danger of Scawby losingall its gulls very shortly. For many years this uniquebreeding ground of gulls, where before the war someloo,000 gulls nested annually, has been a source ofinterest to cycling visitors from all over the country.

Road MaintenanceMAINTENANCE and improvement of the t,t75,969

miles of road and 134 bridges in the County ofHolland, Lincolnshire, cost £151,140 during 1945.The road accident rate was halved during the year.

Road Safety SchemeDROVISION is being made by Lindsey (Lines)A County Council for the expenditure of £750 onroad safety schemes between now and the end ofMarch, 1947.

All the TimeIN the course of a journey the other day, a mother

was heard mildly upbraiding her child for not keepingto the left on her bicycle. " Always keep to the left,"she said. "Always." The kiddie's reaction to thispiece of sound advice was remarkable, for she asked :

Even when going downhill ? " The word " always "was then repeated with greater emphasis.

48 THE CYCLIST March, 1946

My Pointof View

C eu00 sines telesWAS..°

ScoleNorfolk

Looking up the street towardsthe splendid White i-lart-Natal built ,;..1655. Its famoussign spanning the roadway has

,,f,sa.sately long since lam..demolished

Epitaph !T HAVE just been reading an obituary notice whichA speaks of the deceased as " an outdoor man whowas a romantic at heart to the end." I can hardly thinkof a better epitaph. Where's my tombstone ?

Asking For ItTN my part of the world, recently, a cycling post-

oman rode out of a passage and collided with alorry. At the subsequent inquest it was stated that herback brake was missing, while her front brake wasdefective. Any comment on this deplorable state ofaffairs is unnecessary.

So Say All Of UsRATHER belatedly, because other matters have been

more pressing, I quote from a speech made by theMinister of War Transport in the House of Commonslast November, during the second reading of the TrunkRoad Bill : " Our roads must be designed to enablethe motorist, cyclist, and hiker not only to reach hisdestination speedily, easily, and in comfort, but to enjoyevery moment of the journey." If we cannot achievethose purposes, I believe it is because of the conduct ofthe Selfish Few.

Bad SlipI HAPPEN to possess a reputation for being a

methodical sort of merchant. My maps are keptin apple-pie (and numerical) order, segregated as regards(a) England and Wales, (b) Scotland, and (c) Ireland,Mr. Bartholomew's numbering system being supple-mented by the application of plainly -seen dates fromdisused calenders. Similarly, my travel books areassembled on certain shelves in my bookcase, beingagain divided into countries as above. As with mapsand books, so with my gas lamp. The regular attentionit requires is not left until starting -time on Saturdayafternoon or Sunday morning. If the job of cleaning -out and recharging is not done on a Friday evening,the reason is-well, merely that the task was carried outearlier in the week. And, it may be added, the processof recharging applies to water as well as carbide, Ipreferring not to risk being caught napping with regardto a supply of the fluid which is all too common in thiscountry.

So far, so good. The other Saturday, however,Islipped badly. Of course, the lamp required no thouht,it having been attended to, as usual, in ample time.Why, then, did it fail me when a bare two miles of myhomeward journey in the dark had been achieved ?Why was it then necessary for me to take refuge in afriendly garage, dissect the lamp and clean it out,afterwards recharging with carbide and water ? Why ?Because my method had broken down through sheerforgetfulness. The job which seemed to be as much apart of the routine of my life as eating a meal or going tobed had been completely overlooked.

Seen in Time(NNE evening recently, in the course of my journey- home after tea in the country, I had two experienceswhich stressed the need for every unit of traffic to lightits own way, and for every driver or rider of a wheeledvehicle to " watch his step." In the first plate, Icame across a large herd of cows just being released afterthe milking process. In the second place, I found anempty milk -churn lying athwart the road. In eachcase my speed bore such strict relation to the volume oflight I was throwing forward that there was no danger.I saw the cows and the obstructive churn in ample time

to avoid trouble - andthat, I suggest, is butan elementary precautionand duty resting on eachone of us. It is doubtlessan old-fashioned view,but it remains a safe view,and explains one's freedomfrom serious troubledespite many thousandsof miles travelled in thedark.

Mistaken ViewAGIRL cyclist rose

from table at a tea-house one cold dayrecently, gave " Cheerio "to the remainder of thepeople in the room, andmade her exit. " Ugh !shorts!" ejaculateda not her girl who wassitting opposite to me,and who had arrived afterI had commenced feed-ing. By way of commentI raised a bare knee abovethe table-and saidnothing. The girl oppo-site gave a little shiver,and I then explained thatshorts are not so uncom-fortable as they look-granted that they havesuch an appearance-and that I was in thehabit of using them foralmost moo per cent. ofmy cycling. It is quitea mistaken view thatthese abbreviated gar-ments ate chilly.

A Bad WordTWICE within a few days young cyclists have used

the word " inevitable " in speaking to me. Onthe first occasion, my face must have asked a question,for the reply was: " Yes! I've got the inevitablepuncture." I can't imagine what word my friendintended to use-" infernal," perhaps-but puncturesare not " inevitable." The second youngster wastelling me about cycling to work on a skiddy morning.He came round a right-angled bend at speed, and hadthe " inevitable " crash. Of course, a toss is" inevitable " if you ask for it-and that's a thing toavoid doing. I cycled td business on the same morning,doing twice or three times the distance of my" inevitable " young friend, and my machine did notperform a single dither. But, then, I refrained fromapplying for a chance to display my gymnastic abilitiesIt appears to me that " inevitable is a thoroughlybad word. Punctures occur so rarely that it isridiculous to speak of them as " inevitable " : the same -remark applies to skidding.

Britain -boostTT was very interesting to read in my newspaper, atA the beginning of February, of the plan which isbeing launched by the Travel Association for making aseries of films portraying Britain-its sport, industries,and traditional customs-for display in the . U.S.A.and also in Canada andother parts of the Empireand Commonwealth. Thefirst six areas in Britain tobe dealt with are London,the Midlands, Devon andCornwall, Wales, Scotland,and Northern Ireland, astart being made veryshortly with either Wales orDevon and Cornwall, fol-lowed by the Midlands.This is an attractive scheme:it ought to bring manyvisitors to a land which,according to recent Yankee" invaders " (quoted by theDirector -General of theTravel Association someweeks ago) " has moretourist attractions per squaremile than any other countryin the world." By the way,I wonder whether cyclists asa whole appreciate Nature'srich endowment of these" islands of the blessed " ?

Dreams Coming TrueTHIS year of grace, it ap-

pears to me, should seesome of our cycling dreamscoming true-not all ofthem, because many monthsmust elapse before we reachnormality. It does not seemvery likely that Continentaltouring will be possibleduring 1946, but Scotlandought to be reckonedamongst the possibilities forthose of us who live on thewrong side of the River

a '...4;44.14,

Tweed, whilst Ireland may be " on the map." I do notfeel too sure about the latter country owing to the dearthof shipping, which (if it does nothing else) sets upformalities and causes uncertainty and loss of time.Thus, for the moment, I am inclined to view Irelandas a " starter " for 1947-which is quite a tong way off !I say that with considerable regret, yielding to nonein my desire to revisit " the ould sod," which hasentered so largely into my wartime dreams.

r long to see again all those delights with which mymany tours in Ireland have endowed me-Connemara,Killarney, Glengarriffe, the Dingle Peninsula, CountyDonegal, the Bloody Foreland, the Antrim Coast Road,and all the rest of it-but it looks as though the fulfilmentof my dreams will not take place just yet. With regardto Scotland, I have kept away from " t e Land o'Cakes" during the war years solely because of myreluctance to undergo the expense and the discomfort(especially the discomfort) of the long railway journeyfrom the Midlands to (say) Glasgow, and because Iwas not prepared, as a pleasure traveller, to occupytrain space required by those who could (or thought theycould !) answer affirmatively the question : " Is yourjourney really necessary ? " But, with improvingtrain services, the Scotland of which I have dreamed-Galloway, the Trossachs, Mull, Ardnamurchan, Skye,the Great Glen, and " the Road to the Isles "-lookslike being within realisation.

Tram -linesTRAM -LINES are disliked by most cyclists, and

dreaded by some. Yet, given room to manoeuvre,the average steel rail (if there is such a thing as an" average ") need not cause very much concern. Ifyou cross the line at a proper angle, and your tyresare correctly inflated, the job can be achieved safely.If, however, you are hampered by other traffic,difficulties may arise. My own policy is one of refusingto be stampeded into doing the wrong thing. I preferto stand by until (if it is necessary to cross) tram -linescan be approached at an angle which experience tellsme carries safety with it.

The Better PartVARIOUS harrowing stories have been heard relative

to the wartime (and post-war) difficulties overmeals as experienced by people who take non -cyclingholidays-of the inability of certain company -housekeepers to supply more than bed and breakfast, and ofthe necessity for queueing up at restaurants, etc., inorder to obtain lunches, dinners, and teas. As a cycle -tourist who has taken his full quota of holidays, it maybe placed on record that no such problems have come

queued for a meal : I havenever been " driven from home " at places where Ihave stayed and been asked to get my food out. Therehave been one or two slight-very slight-difficultiesover accommodation, but only on one occasion did Imiss a meal, and that was at a seaside resort, where,having regard to my views about such, I had no right tobe ! Here, after sitting in a restaurant waiting for a mealwhich was an unconscionable time a-coming-theanimal involved was still roaming the mountains whenI entered the place, and had to be rounded -up, captured,disrobed and cooked !-I indignantly went on my way,expressing my feelings in suitable language to theproprietor, who had the effrontery to inquire whetherI had enjoyed my lunch ! An " iron ration " ofchocolate kept me going until tea -time, when I madeamends for the meal I had missed.

.0.15 4,ure winDa.* behial Ova

Wriest Lewes awd Esilyarns.

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