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110 NEWNES PRACTICAL MECHANICS January, 1944

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NEWNES PRACTICAL MECHANICS

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PRACTICALECHANICS

111

to the kaper shortage " The Cyclist," "Practical Motorist," arri "Home Movi,-.3" are= temporarily incorporated.

Editor : F. J. CAMM

VOL. XI. JANUARY, 1944 No. 124

BY THE EDITOR

Wanted-A Square Deal for InventorsIWAS interested to receive a copy of a

pamphlet entitled Wow Inventors CanAid the War Effort," from the U.S.

Department of Commerce. I read thispamphlet with great interest, for, as readersknow, I have always held that inventors inthis country have been badly treated byGovernment Departments as well as vestedinterests. I am not, of course, referring tothose stupid " inventors " who imagine theyare inventors because they bend a nail in. anew way to act as a coat -hook. I am refer- 'ring to inveptors with scientific knowledge,education and practical training who are ableto puceive, ' without harassing manufac-turers (and editors!), whether their ideas arepracticable. Invention, of course, does notnecessarily mean the creation of somemechanism or, principle ; it also meansdiscovery.

I was interested in this pamphlet for tworeasons. It indicates that the inventor hasa far better time in America, even duringthe war, than do inventors in this country.Inventors in Germany were for many yearsbefore the war subsidised by the German.Government. In America there is theNational ' Inventors' Council, which .is acentral Governmental Clearing House to'which can be submitted inventions andsuggestions that might prove valuable to thewar effort. It was created in August, 1940;by the Secretary of Commerce with the fullconcurrence of the President. The Councilmembership comprises outstanding Americaninventors, scientists and industrialists havingwide experience in the .development andutilisation of invention, and the ,high profes--sional standing of these men, all 'of whomserve without compensation, inspiresconfidence in the ability of the Council to

s do the job for which it was created. The1 primary function& of , this Council is toencourage the American public to' submitinventions or inventive ideas of value in thewar effort, and promptly to evaluate theseinventions by a system of technical corn--mimes so that useful ideas may be promptlyplaced in the hands of the proper militaryor naval bureaux. A central file of suggestedinventions is kept, as it is considered to beof continuing value.; if not in war, then inpeace. It is noted that. in 16 months ofoperation the Council received over 90,000communications, of which about 55,000contained inventions and ideas. A surpris-ingly ldrge percentage of these havepossessed sufficient merit to warrant seriousconsideration. A number already have been

accepted for use by the American Army,Navy, Air Force and other GovernmentDepartments.

Stimulating Inventive EffortTHE Council is desirous of stimulating

inventive effort on the part of thenation's inventors, scientists, engineers, tech-nicians and mechanics. Experience hasshown that useful suggestions are generallymade by men having technical training aswell as practical experience in one or moreof 'the various branches of science andengineering. It is recognised that valuableideas may spring from any. other source, andtherefore careful attention is given to everysuggestion submitted. -Each of these isacknowledged, classified and referred to oneor 'more staff engineers for careful examina-tion and evaluation. Those appearingmeritorious are ,hen referred to the appro-priate technical committee chairman for hisconsideration and report, and when hereports favourably it is referred to ',theCouncil as a whole. If the Council affirmsthe'chairman'srman's opinion, the invention is thenforwarded to the various Services for theirconsideration and ultimate adoption if theyfind it acceptable. In the latter case theService Department deals directly with theinventor in making the necessary arrange-ments for the use of the invention. TheCouncil does nor' consider the question ofcompensation, or contracts between inven-tors, and the Army or Navy. This isnegotiated by the appropriate Service orauthority. The kind -of inventions whichmay be found useful are improventents indevices or methods now in use 4nd newdevices or ideas not now known or used,but which may be found useful. Thosemost 'likely to be found acceptable are thosebased on a knowledge of the particular field.in which they lie plus some knowledge ofthe military requirements surrounding theiruse ; and those based on entirely new butsound conceptions which -may be so promis-ing that military requirements and strategycan be planned to utilise them. New ideas,however revolutionary, are always welcome,but inventors should guard against thecommon fault of thinking that merelybecause their invehtion is different, it 'mustbe better than another device already in usefor the same purpose. Military require-'ments sometimes preclude the* use ofdevices which may give satisfactorylaboratory performance.

Most of the items_ of military equipment

have been devised and developed by-civilians, and in some cases by those whohave had no experience in military affairs.Well-known examples include the aeroplane,the machine-gun, smokeless powder andrifled cannons. Many ideas have beenbrought to a state of important usefulnessthrough, the assistance of the well-equippedengineering bureaux of the Army and Navy.

Hundreds of industrial companies, labora-tories, engineering firms and inventors areengaged in the task of developing, newproducts arid 'processes for commercial andindustrial use, but many fail to realise theapplication that these inventions may haveto the needs of- the armed Services. Themilitary, naval and other establishments ofthe United States Government have such

, extended ramifications', that almost any newindustrial idea' is likely to be of some interestto them. The Navy yards and arsenals do

' work which demands the greatest precisionand most modern. methods.

For this reason it is suggested that headsof research and development departments ofindustrial companies, trade associations,engineering firms, or private laboratoriesreview each new industrial discovery fromthe standpoint of its application to military,naval or other Governmental needs. This,of course, does not apply to work that -isbeing currently done for the militaryServices, but only to that which would notautomatically come to the attention of thesebranches. Disclosures of such discoveries orinventions should be sent to the NationalInventors' Council. They will be givencareful consideration for their applicabilityto the national emergency. The system ofcommittees and liaison officers establishedby the. Council enables this exploratory orevaluation work to be accomplished withthoroughness and dispatch.

There is ' little encouragement in. thiscountry for inventors:. The Government haspower to- commandeer any invention with-out compensation to the inventor, althoughas a Tact, when the war is over, the inventorcan apply for compensation. If he - doesmake out a case this is usually- granted, but,owing to the large number of applicationsreceived for compensation, it often takesyears for the application to be heard.

If it is necessary to encourage inventorsin war, which is purely destructive, is itnot even 'more desirable to encourage themin peace ? We are, longer at peace thanwe are at war, and the needs of peace aregreater than war.

112 NEWNES PRACTICAL. MECHANICS January, 1944

Small Wind-power PlantsSimple Methods of Eilding Small Wind -power Plants from Scrap

Material with the Minimum of Tools

By W. H. SUTHERLAND

WINDCHARGERS are divided intoW two main classes - geared and

directly driven. Geared units areso difficult to build without unusual facilities,Fnd depend to such an extent on the oddsand ends of *machinery available that noattempt will b.-. made to describe their

Fig. 1.-Diagrams explaining the removal of'third brush from car generators. Dotted lines

show new connections.

construction. On the other hand, a' directly -driven dynamo must begin to charge-below 50o r.p.m. to make use of light winds,so the choice of dynamo is fairly limited:

'Choosing a DynamoDynamos off old cars generally have a

low charging speed, but are usually builtfor 6 -volt working. A modern 12 -voltdynamb does not cut -in before 9oo r.p.m.,but may be slow enough when used On a6 -volt wind charger. There are severaladvantages in using a 12 -volt dynamo on ab -volt circuit. Such a unit will be chargingat currents up to 4 amps in winds thatwould not cause the same dynamo to cut -inon a 12 -volt circuit, and as summer monthsbring weeks of these light, steady winds,the advantage is obvious. The heating effect

uR,

in the field -coils is only one quarter asgreat as it would be at 12 volts, so thereis practically no danger of the dynamoburning out. Also, since the magnets get,at most, half of their correct magnetic flux,the current will reach a maximum value atabout 15 to 20 amps, and even twice the

propeller speed will not cause muchincrease. This protects both armatureand battery cells. Lastly, it is muchcheaper to build a 6 -volt outfit.

In choosing a dynamo there are certainpoints to watch that give a rough idea ofits value for windcharging. Generally aslow dynamo has a large diameter caserather than a long one. The armature iswound with wire of about 18 S.W.G. forslow charging, while faster ones have a

.S.W.G. winding. There seems to belittle difference in cutting in speedbetween 2 -pole or 4 -pole construction.To test a dynamo, wind a yard or

two -of string around the axle and giveit a strong, steady pull. A sudden jerkshould be felt as the dynamo gathers speed,and after dtat it should only be possibleto rotate It comparatively slowly with thestring. After trying several differentdynamos it is easy to judge which ones are

General viewview of the, large model to be described in the next article. Full details for building'and winding the dynamo will be given. A Lucas A 900 C or A 80o C dynamo is needed.

(Above) Two views of the 6 -volt windchaverdescribed in .the text. Built with a LucasC 45 A type 12.5 dynamo, cutting in about450 r.p.m. The top illustration shows thewindcharger suitably mounted several, hundred

yards from the house.

slow. A fast dynamo will continue togather speed until the string is nearly offbefore beginning to generate.

For comparison purposes, remember thatthe maximum speed' possible when turninga dynamo by hand is about 30o r.p.m.Commercial windcharger dynamos willcharge at this speed, but no ordinary cardynamo would register more than one voltat 30o r.p.m. The dynamo should light a12 -volt 24 -watt bulb easily when turned bystring in this manner. See that it has goodball -bearings at each end, and that the

January, 1944 NEWNES PRACTICAL MECHANICS 113

backward pressure of the wind on thepropeller will not displace the bearings. Thecommutator should show no sign -of a groovewhere the' brushes press. The axle mustproject far enough from the case, and havesufficient screw -thread to allow for securefixing of the propeller.

Overhauling the DynamoDismantle the dynamo and remove any

oil or carbon dust. If the mica insulationin the commutator grooves is level with thecopper surface, cut it down with a pointedtool. For windcharger work, the third, or" regulation " brush is removed to lower thecutting -in weed and to reduce wear. Thisbrush is connected directly to one end ofthe field -coils, and is movable and usuallysmaller than the other two. Trace the field -coil connections in series through the twoor four coils, and find where the end remotefrom the regulation brush is connected. Ina two -pole machine it is usually earthed tothe case, but with four -pole constructionit will be joined to the main positive brush.j,,eave it where it is. Remove the other endof the coils from the regulation brush andconnect it so that the coils are across thetwo main brushes. The third brush -holdercan then be removed altogether. Fig. a.makes this procedure clear, the dotted lineshowing the new. connection in each ease.Test the dynamo again with string.

[sin. lengths of flat iron bar. Pieces of farm -cart wheel -bands are suitable, and anyblacksmith will bend them to the requiredshape. The bars are clamped around thepipe as shown in Fig. 2, using two in. bolts.They should be flat against ' each other onthe long side, but have a clearance of lin.on the short side, to allow for tightening.The long side should be long enough forthe particular dynamo used. The dynamo isfixed to the turntable by a pair of rings,shown in Fig. 3. These are made fromany light strips of iron, about tin. wide andlin. thick. The turntable for the smallwindcharger shown was made with a solidiron bar- instead of the inside pipe. It isattached to the flat cross -bar carrying thedynamo ,by means of a large nut and split -pm. It was part of an iron bed, and hadabout 'lin. of one end threaded. The tubecarrying the tail fin can be attached bysmall bolts to the short end of the cross -arm.It should consist either of light, circulartubing, or right-angle iron, to preventvibrations being set up in it. Four feet isa suitable length for a small turntable.

The Tail FinThe tail fin is made of any -strong, light

material, and is about aft. square. A biggerfin will put unnecessary strain on thedynamo axle when changing direction due tothe gyroscopic effect of the propeller. When

Fig. 3.-Showing methods of attaching dynamo to turntable described, and to a .flat bar, asin the model illustrated.

It is useful to know that the direction ofrotation of the dynamo is reversed by inter-changing the ends of the field -coils, sinceit may be necessary to do this when chang-ing from chain gearing to cog -wheel gearing.A dynamo which has been idle for longoften fails to work because the trace ofmagnetism necessary to start the field cur-rent is absent from the pole -pieces. Toremedy this, connect it with correct polarityto a car -battery and allow it to spin as amotor for several minutes. Finally, give thecomplete dynamo two or three coats of goodenamel, after making sure that all screw -holes or other openings are closed to moisture.

TurntableThe turntable is the part of t,he outfit most

likely to cause trouble. The writer hasfound that complicated fittings, for example,ball -bearings, should be avoided, and thatno timber should ever be used in the con-struction. The final details depend entirelyon the material available, and general con-structional hints are all that can be given, inan article like this. A convenient form ofturntable consists of two lengths of ironpipe, about 3ft. long and t 1- to tins. indiameter. They need not be a very accuratefit, since a little rocking will cause nodamage. The outside pipe is blocked by awooden plug at the bottom to form an oilreservoir, and can be fixed easily to av.00den pole, as shown in the illustration(Fig. 2). The inside pipe 'is blocked simi-larly at the top to prevent the entry of rain.

To secure ths dynamo to the inside pipe,a cross -arm is needed. This can be made byputting semi -circular depressions in two

mounted, the turntable is filled with heavylubricating oil. Every constructor will findmethods of his own for' building a simpleturntable, but the points given can formthe basis for individual design. No mentionhas been made of slip -rings to carry thecurrent from the turntable. During a year'scontinuous running with the windchargerillustrated, the author had only once tounwind the direct connections going to thedynamo. Heavy rubber -covered leads wereused, sufficiently long to loop easily around

the turntable pipe should the wind changedirection by a complete revolution.

Propeller DesignIn spite of the general opinion, a pro -

4' -- 2. 2

4i- Space tor. Tightening'

Wooden Pmg to....../Keep Out Rain

2'

Fig. 2.-Method of making a simple turntable.

peller is quite easy to make, and so longas the -fundamental principles are adheredto, wide variations of slope and dimensions ,are possible. I shall give details of twotypical types, a very fast one for the smallwindcharger described, and a more powerfulone, not so fast, for rewound or . geareddynamos. After one or two attempts, theconstructor will get the knack of propellermaking, and will be able to introduce altera-tions. The first essential is a sound board ofuniform thickness, with the grain runningalong the length. Douglas fir is the besttimber, but well -seasoned ash is a goodsubstitute.

For very high speed running, 5ft. bins. isa good length, but a 6ft. propelleris a better all-round source of power, andcan easily be cut back a few inches ifnecessary. Both propellers described rotateclockwise. For the fast one, a board 6ft. x4ins. x in. is needed, but the slower typeneeds a board 6ft. x 4lins. x tin. Findthe centre and drill a fin. hole for testingthe balance' by hanging the propeller on anail in the side of. -the bench. The propellershould return to the horizontal froin anyother position, and it is essential that thistest be done, and any deviation correctedafter -each separate operation in making thepropeller. It is not sufficient to balancethe finished propeller by removing sometimber at random from the heavier side.Mark the board as shown in Fig. 4, andsaw off, the shaded portions, cleaning thesaw cuts with the plane. Along eithertrailing edge, mark off from the table thedistances shown, measured from the backsurface of the board, and join them witha pencil line. To form the driving slope,the front of the propeller must now beplaned down so that a flat, smooth surfaceconnects the o iginal edge C D of the boardto the' pencil line all the way along eachblade. The space G F C can best be" scoope " out with a spokeshave, but a

6

M F

Trading Edge

H

Front

C Leading Edge

rE

Copper Foll

Distances Usedin Table

Fig. 4.-Propeller details. Note.-The curve of the leading edge remains the same at each section.Fasi type. x =3in., y l= fin. Slower type. Y =4iin.,

Removed BeforeShaping Backto Lighten Tips

L.E

i


ti

small plane will also do. The flatness ofthe new surface is tested with the edge of aruler, and should be fairly true all theway along. The cross-section, of the boardat various points is shown in Fig. 4. Thiscompletes the driving slopesof the propeller,and it only remains to shape the back forthe lowest possible air -friction. The dottedlines on the treks -section diagrams show thefinal shape of the back surface, which

is planed into a smooth curve with a" blunt " leading edge and decreasing rapidlyaway to a point along the trailing edge,the maximum thickness of timber beingabout one-third of the width of the bladefrom the leading edge at all points. In order

lines can now be worked on to the back ofthe blades. Cut the tips of the blades tothe shape indicated, and the propeller isready to be sandpapered. This should becontinued, from coarse paper to fine, untilthe whole propeller has a glass -like surface.Particular attention should be given to thetips of the blade, where the speed is greatest.If a suitable piece of light copper or leadfoil is at hand, the leading edge should beprotected for the last 12ins. of its length.The foil must be bent to fit the shape ofthe blade perfectly, extending back aboutA,in. on the blade, and fixed by about sixsmall wire staples, passed through tiny holesdrilled through the foil and timber, andBOARD DIMENSIONS,

seldom need to be shut off to avoid over-charging, but a light rope can be left hang-

'ing from the tail to tie the machine per-pendicularly to the wind direction, or tounwind the dynamo connections if theYshould ever become wound around the turn-table. It is absolutely necessary that thewhole installation be wired with theheaviest possible wire, and on 6 -voltcircuits there is no need to have coveredwires, either outside or inside, providedthere is no danger of opposite polarity wirestouching. This makes possible the use of7/22 bare aerial wire, which can beobtained cheaply.

A small unit of the kind described above

Distance from centre of board ... ! 2 i 3 1 4 ' 11 1 5 1 6 1 7 8 1 9 1 10 1- 11 12 13 1 14 ! 15 1 16 17 i 18

Distance from.back surface on T.E. 1*.75 i .75 1 .751 .25 1 .10 1 ..06 1 .06 I .06 r---.IF,1 .22 1 .24 : .26 -1 .28 1 .30 1 ..31. 1 .32 .34 i .38

Distance from centre of board ... 1 19 1 20 21 [ 22 1 23 1_24 1.._ 25 ,. 28 - ; 27 28 1 29 30 1 31 1 32 1 33 34 135 36

Distance from back surface on T.E. 1.39 1.40 .41 i .41 I .41 1 A2 i A2 ; 44 .M .55 I .57 1 .58 1 .59 1 .80 1 - .60 .61 1 .62 1 .62

BOARD DIMENSIONS 60 1

Distance from centre of board ...:1 2 3 4 41 1 5 6 7 8 1 9 , 1

--- "

10 . 1 11 I 12 1- 1.3 , 14 I 15 1 16 t 17 18

Distance from back surface on T.E. 1 1 1 1 .60 1 .50 .20 .10 .10 1 .12 1 .13 M6 1 .2 1 .2 I .2 1 :22 1 .23 .25 .27Distance from centre of board ... 1 19 1 23 1 21 1 22 i 23 21 ; 25 26 1 27 1 28 1 29 30 1 31 1 32 i 33 1 34 35 . M

Distance from back surface on T.E. : .35 1 .4 1 . 42 .43 . .45 1 .19 . -.50 . .52 1 .54 .60 1 .65 1 .70 1 .71 1 .73 1 .76 1 .76 1 .76 1 .78

to reduce the weight of the outside portionsof the propellers and to maintain the correctproportion between thickness and width,some timber has to be removed from theback before shaping to the streamline sectiondescribed. -Lay the propeller with backuppermost and put two or three blocks oftimber underneath the front face to act assupports, since the driving slopes will notlie flat on the bench. Plane the board,keeping a_ flat surface, until it changes fromits original thickness at the centre to abouthalf of its thickness at the end of eachblade. This will compromise betweenstrength and lightness so that exact detailsare best decided individually.

The streamline curve illustrated by dotted

clenched on alternate sides. This protectionis almost a necessity, since the timber comesto pieces along the leading edge afterseveral months working. Give the propellerat least two coats of good outside varnish.If the first coat is not properly hard beforethe second is added centrifugal force willdrive the varnish into ridges underneath thelay& formed by the second coat. A weekshould be enough to dry each coat. Attachthe propeller to the dynamo by whateversystem is most suitable to the particulartype .used. Generally, a *in. plate, held onthe dynamo axle by the' nut that securesthe pulley wheel, and attached to the pro-peller by two tin. bolts spaced by about4ins. is quite sufficient. Small windchargers

is only suitable for supplying a few lightsin good wind areas, but on account of itssimplicity and strong construction, it ispractically trouble -free in use. The dynamowill not begin to charge, until there is aStrong wind blowing, with the propelleralmost invisible. At thi3 point,, let meremark that a windcharger propeller is'never rotating as fast as it appears to berotating when viewed from a distance. Nextmonth the author will describe in detailthe complete construction of a larger unit,using a re -wound Lucas A 90o C dynamo.Full winding instructions will be given forthis particular type, which is - very suitable.

(To be continued.)

How Many EnAines?The Possibilities of Multi-engined Aircraft.

NOT so very long ago a single -seatermachine with more than one motorwas quite unheard of, and for multi-

engined aircraft the tri-motored layout heldthe field. Those readers who recall thefamous Fokker monoplanes, and theirbrilliant record in all parts of the world, maystop to wonder why the three -motor layout,one engine in the nose and one slung undereach wing, has been abandoned in favour oftwo or four motor installations, generallymounted on the wings. The only notablesurviving tri-motor machines at the presenttime are the Junkers Ju. 52B, and certainItalian machines, all now admittedly obsoleteof obsolescent.

Single EnginesIn the early days it was purely a question

of the power which could be derived from oneengine. Two such engines were not quiteenough and so three was the logical choice,although it was soon realised that the centreengirtc, mounted in the nose- of the machine,was less efficient than the other two due to thepresence of a fuselage behind it. Whatactually happens is that the velocity of theslipstream from an airscrew is greater thanthat of the airspeed of the machine. Thugall components exposed to the slipstream haveincreased drag (drag being proportional to the

By NEMO

square of the velocity of air flowing over thecomponent) and greater drag means lessefficiency. From this general description itwould appear that the pusher layout withthe pusher airscrew, now truly to be termeda propeller, at the - rear of the fuselage orengine nacelles, would be the most efficientlayout, but this will be dealt with in moredetail later.

Systems of MountingRealising the inherent inefficiency of the

orthodox tri-motor layout many designersadopted different systems of mounting theengine. The most obvious solution, stillkeeping to the tractor arrangement (i.e., withthe airscrew in front) was to raise - all theengines clear of obstructions suitably mountedon struts. Examples of this are seen in theShort Calcutta and Saro Windover, to namebut two. The engines are then set in lineabreast with only the tail unit under theinfluence of the slipstream. This, obviously,was not the ideal solution, the struts themselvescontributing a large amount of excess drag.The next step was to Taise the wing above thefuselage and set the engines in line in thewing, as in the Supennarine Air Yacht of1932 or, a more modern example, the

Dornier Do. 24. Both of theie machines areflying -boats, and thus this form of enginemounting not only grouped the engines in anefficient manner, but also raised the aftscrewsclear of spray. Spray thrown back on torevolving airscrews is harmful, pitting orotherwise damaging the blades and shorteningtheir useful life.

A . third' class of tri-motor designs isdeserving of mention, if only on account ofits quite unorthodox appearance. In this thetwo outboard engines are mounted under orbetween the wings in the normal manner, butthe third engine, instead of being mountedin the'nose is mounted above, or on the upperwing. In this country we hadi the AirspeedFerry, which did much useful work with certainair circuses, and in America the Ford 24-A.

However, the tri-motor layout has nearlydied out and apart from the notoriousJunkers ju. 52, which is reckoned " easy -meat " to the modern fighter, the Italians areabout the only country which has persistedin such designs. Indeed the Savoia MarchettiS.M. 82 Canguru, a normal tri-motor,low -wing monoplane, holds a number ofweight -carrying and distance records, outstanding amongst which is a flight of 8,037.97miles in 56i hours in a closed circuit in 1939.But in general the tri-motor layout has almostdisappeared.


:With the greater power output availablefrom single engines it has been found thattwo engines of, say, 900 h.p. each gave abetter performance than three engines of600 h.p. each, although the total h.p. is thesame. Experiments were performed on anumber of aircraft during the early 1930's totest such assumptions, flying one particulartype with one, two and three engines of thesame total power. In all cases it war foundthat two engines gave the better performanceand thus the twin-engined layout approachesmore nearly the ideal.

Four-engined LayoutWith the recent increase in -size of heaVy

bombers, and in spite of the increased powerof single power units, the four-engined layouthas become standardised. America Was oneof the first countries to take this step, aBoeing B-299, the direct ancestor of theBoeing Fortress, being first flown in 1935.Now in this country we have, of course, theAvro Lancaster, Handley Page Halifax, ShortStirling and Short Sunderland, in addition toseveral American types.

In spite of the outstanding performance thefact remains that all of these four-enginedmachines would be more efficient and have abetter performance if fitted with only twoengines, of the same total h.p. In point offact, the Halifax and Lancaster were originallydesigned as twin -motor bombers around theRolls-Royce Vulture engine. This enginefailed to come up to expectations and has beenabandoned, and hence, since no suitablesubstitute was available in quantity, both ofthe types concerned were fitted with four Rolls-Royce Merlins. The total h.p. of fourMerlins exceeds that of two Vultures of theoriginal design layout, and thus performancedoes not suffer. However, two Sabre enginesof 2,400 h.p. each, replacing the four Merlins,would probably give an increase in per-formance.

The reason for this is not hard to find.In the first place, additional engines,. meanmore weight, more accessories and, naturally,more cowlings and nacelles to spoil theaerodynamic form. Thus both drag andweight are increased, so performance naturallysuffers. This is not always true, for it maybe possible to use Tour engines of, say, 500 h.p.each which weigh less than two engines of1,000 h.P. each, but the greater number ofauxiliary fittings and decrease in aero-dynamic efficiency is still to be countered.

Thus at the moment it would seem thataircraft design for large multi-engined

View of the assent5ly line in one of the Ministry of Aircraft Production factories, showing four-engined Lancaster bombers invarious stages of completion.

machines has got ahead of engine design,but this is really only a. case of production.Aircraft design waits upon engine design, asit has always done in military aircraft (anda large number of civil types), but there are anumber of 2,000 h.p. and over engines goinginto production, which figure will probablybe still further increased in the near future.

Dotible-engined NacellesIn the meantime certain designers have

looked for other solutions. 'The HeinkelHe. 177, one of Germany's latest four-engined bombers, is, from external appear-ances, a twin-engined machine, with a nacelleslung under each wing. Actually eachnacelle houses two motors, each pair ofmotors being geared to a single four -bladedairscrew. In this manner four engines areemployed in an aerodynaihically efficientmanner, although the question of weight* ofcomplication of gearing still arises.

The other example is the Dornier Do. 26,which has four motors arranged in twonacelles. Each nacelle thus contains twomotors, but each motor drives its ownairscrew. Thus there is one airscrew at theend of the two,nacelles, two pushers and twotractors. This again is a compromise, butalso affords an illustration of the greaterefficiency of the pusher layout. With fronttractor airs crews stopped and pusher airscrewsdriving the top speed is greater than thatwith pusher airscrews stopped and tractorairscrews driving. In other words, the pusherlayout is more efficient, i.e., has less drag.

Readers may remember the American BellAiracuda introduced some years ago, which, isa fairly orthodox machine with twin motorsin nacelles attached to the wings, with theexception that the airscrews are behind thewing (i,e. pusher) and not in front. Thisarrangement has been proven to gide greateraerodynamic efficiency, but here arrives abig difficulty which apparently has beenoverlooked on such designs. Owing to theposition of the airscrews it is practicallyimpossible for any of the crew in front ofthem, i.e., in the nose of the machine, to baleout without hitting the airscrews and beingcut to pieces. It may be argued that on theAiracuda design provision might be made foran escape hatch in the fuselage aft of theairscrew discs, but for other similar designs,such as the Fokker D 23 push-pull single -seater fighter and certain projected designs,such a solution is not possible.

Hence, in spite of the proven increase inefficiency, it would appear that the application

of the pusher layout is somewhat limited,unless it is possible to ensure the air -crew areasonable chance of baling out clear of theairscrews.

That greater size means more power neededto maintain flight is easily understood, andalso that greater power means betterperformance, but within a short timeto,000 .h.p. or more should readily beavailable from four engines and so, exceptfor outstanding developments in design, thereshould be little need to include more thanfour engines on a large machine.

Multi-engined MachinesHowever, for various reasons aircraft films

will build bigger and bigger machines andso undoubtedly there will be, six-enginedmachines ; there are actually a number at themoment of writing, such as the Blohm andVoss By. 122, and even eight-enginedmachines. Six- and eight-engined machineshave been built and flown successfully longbefore the present war, and the DornierDo. X had 52. Several of this design werebuilt, three for Italy, but in spite of a totalof 7,200 h.p. from its 12 engines, it wasunder -powered. The multiplicity of engineswas primarily due to lack of suitable high-powered engines at the time, hence a largenumber were used to give the required totalh.p. To -day the four engines of the ShortStirling deliver nearly the same power as the 12of the Do. X (6,400 h.p.), and if it had beenpossible to fit these to the Do. X they wouldprobably have given a better performance onaccount of reduction in drag and weight.

To talk of the future of multi-enginedmachines it would appear that with theever-increasing size it will be possible to.house the engines completely within thewings, and this will approach the ideal. Onsuch' an arrangement the airscrews, eitherpusher or tractor, will be driven by extensionshafts, and the only notable extrusions willbe the necessary cooling radiators, etc.Apart from consideration of weight andstructural design the question of duplicity ofengines will then be simplified.

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London, W.C.z.


Airship Development

The R -too at the mooring mast in Montreal,after her remarkable trip from England

in 1930.

THE quesuon as to whether airships willbe utilised in the future is interesting,and -quite a good case can be made

out for their use. Freight which is not ofa compact form may be delivered by airshipat lower speeds than is possible by -heavier-than-air machines, but at the same timethree or four times faster than normal landor sea transport. Prior to -the presentconflict, due to several catastrophes; theairship looked as though it was becomingextinct, but a review of its development,advantages and disadvantages follows.

DevelopmentVery shortly after the first successful free

balloon flights had been made severalinventors began to tackle the problem ofcontrolling the direction of flight so thatplanned journeys could be made. Althoughballoons have flown hundreds of miles andascended to the stratosphere, they arealways at the mercy of the wind.

A steam engine enabled the first airshipto. fly under its own power in 1852, butvery little success was achieved until thelatter part of the nineteenth century,when the internal-combustion engine wasdeveloped. The first important step wasthe change from the spherical form of theballoon to a more streamlined form, whichenabled the resistance to be lowered and thecontrol to be improved,.

It was soon found that as the size ofairships was increased, difficulty in main-taining the shape .of the gas container wasexperienced. This type, known as the non-rigid airship, was nothing more or less thanan ordinary balloon with a passenger basketand engine hung from cables attached tothe fabric. Due to the variation in thepressure of the gas caused by the heat fromthe sun or the release of gas for manoeuvringpurposes, the envelope may sag or otherwiselose its shape. Also, if the pressure becomestoo high the fabric may split and allow thegas, to escape. This danger occurs whenthe airship rises, owing to the reduction ofthe air -pressure causing the container toexpand and tend to burst.

Non -rigid AirshipVarious methods of overcoming some of

the difficulties described in the previousparagraph encountered in the non -rigid typeof airship have been developed. In orderto maintain the nose profile; wooden or metalstiffeners may be incorporated at this portionand prevent the air pushing the fabricinwards, thus maintaining a good entry.

To prevent the pressure inside the con tainer rising to a dangerous figure as the

airship gains altitude, valves are fitted whichallow the excess gas to escape. Unfortun-ately, when the airship descends the volumeof the gas will decrease and cause theenvelope to collapse. To counter this lastdisadvantage balloonets (small air bags) arefitted inside the envelope. By filling thesecontainers with air, the correct profile ismaintained.

The use of these air bags during ascent.prevents waste of hydrogen, as the air may

Elevators

Fin and Rudder

The Possibilities of the Use ofAirships in the Post-war Years

By T. E. G. BOWDEN

These airships were very successful, and,when powered by two 240 h.p. engines, flewat almost 6o m.p.h., with a duration of 24hours. The capacity of these patrol airshipsvaried from 10o,000 cu. ft. to approxi-mately 400,000 cu. ft. They are idealfor coastal patrol work, provided that theyare not likely to. encounter opposition fromenemy aircraft, as their envelopes areextremely vulnerable. On the other hand,their ability to remain stationary is animmense advantage when searching for'submarines.

The materials utilised for the envelopeshave not changed from those used in theearly days. Doped fabric, with layers ofrubber between them, have proved satisfac-tory. For manoeuvring purposes; fins,rudders, tailplanes and elevators have beenstandard fittings, and function in a similarmanner' to those used on heavier-than-airaircraft.

In 1925 several non -rigid airships wereconstructed in the United States for corn-mercial purposes and achieved considerablesuccess. One of the Erst of these passengerairships remained in operation for six .years.The capacity was II2,000 cu. ft. andlength 14oft. The U.S. Army Air Corpsflew non -rigid airships with several interest-ing features. To allow for a landing on thesurface of the sea the passenger car was

Gas Valve

Car and EngineFig. 1.-Non-rigid airship.

be allowed to escape and make room forthe expanding gas containers. Fig. r illus-trates the general outline of a typical non-rigid airship. 'During the last war (1914-18)this type of airship was used extensively forpatrol work over the sea, and the Americansare using them for anti -U-boat flights in thepresent conflict. The speed of these airshipsis approximately 5o m.p.h. and the capacity6o,000 cu. ft., giving a useful lift of halfa ton.

A development of the non -rigid airshipwas the type designed by the Astra-TorresCo. Instead of having the usual -circularcross-section (Fig. 2), a trefoil section wasused giving three lobes. Internal fabricdiaphragms were fitted to maintain thisshape, and holes cut, so that in effect therewas only one gas container. By adopting thisdesign the necessary rigging for the attach-ment of the car and engine was allowed tobe partly inside the envelope due to the loaddistribution obtained in this type. By doingthis the drag was considerably reduced,although the. constructional difficulties were_increased.

Fig. 2.-Trefoil section airship.

shaped in the form of a boat, and walkwayswere provided so that the engines could bemaintained in flight. A small observationcar was carried, capable of being loweredfrom the main car by means of a cable andan auxiliary motor. An extremely interestinginnovation was the introduction of a methodwhereby water could be picked up duringflight for ballasting purposes.

Semi -rigid 'AirshipAs the si?..e of airships became greater, the

need for some form of stiffening becamemore apparent and led to the introduction ofthe semi -rigid design of airship. The mainfeature of this type is a girder which extendsfrom the nose to the tail. A typical keelgirder is illustrated in Fig. 3. By thismeans the profile may be% retained moreeasily and also the pressure required .in thegas container may be reduced, thus avoidingstraining the fabric.

Two Frenchmen, Pierre and PaulLebaudey, constructed one of the first semi-rigid airships but it. was not a very greatsuccess. The disadvantage was due to the


amount of resistance caused by the stiffeningmembers, which were external. The speedwas, as a result, not very great and also,due to the lack of knowledge of the forcesacting on the structure, the flexibility wasexcessive.

The Italians developed a more successfulsemi -rigid type by enclosing the keel insidethe main envelope, thus reducing the resist-ance. At the same time the passenger caruas attached close to the keel and by thismeans a fairly satisfactorY streamlinedshape was obtained.

One of the largest semi -rigid airships to beconstructed wa the Roma (Italian) with acapacity of one and a quarter million cubicfeet. The length was 4t oft., speed 70 m.p.h.,and the lifting force approximately 4o tons.This airship was designed for ocean travel,but after being sold to America wasunfortunately destroyed by fire.

The hydrogen in this type may be carriedeither in separate containers or in one largegas, bag separated into several sections byfabric diaphragms. An extremely successfulairship, the Nore, had to gas compartmentswith a total capacity of almost 700,000 cu.ft. This airship flew vast distances overthe Polar regions in all climatic conditions.

A nose cap attached to the keel helped tomaintain a good nose profile.

Rigid AirshipsFrom the semi -rigid design of airship, the

next step was the rigid type illustrated in.Fig. 4, and developed mainly by, the German,Count Zeppelin. In this type a metal frame-work is installed which carries all the loads,thus making an extremely stiff and strongstructure. Transverse frames built fromlight alloy are connected to each other by_means of a series of girders running fromthe nose to the tail. Additional wirebracing is fitted and a layer of fabric spreadover the frames. The outer envelope neednot be gas -tight as its main function is toprovide the correct profile,

A typical successful rigid airship was theHindenburg with a capacity of 7,000,000

Longitudinal Girder

The U.S. Army dirigible RS -1, soaring over Washington after a flight from LangleyField, Virginia, several years ago.

Various methods to overcome this difficultyhave been tried out and one solution is tocondense the water in the engine exhaustsinstead of discharging it to waste. An inter-esting method was the one used by the GrafZeppelin. Instead of using normal liquidfuel, a gaseous fuel was used which possesseda density approximately the same as thatof the normal atmosphere. Consequently,the consumption of fuel did not affect thelifting properties of the airship.

All -metal AirshipA departure from the usual airship design

was the introduction of an all -metal airship.The problem of covering the framework witha thin metal 'skin required a great deal ofexperimenting and research work beforesuccess was achieved. Originally, in America,a skin of duraluminium o.co8in. -

thick was suggested, butdifficulty was experienced, due Longitudinalto corrosion. Members

Reinforced Nose

cu. ft. of gas. Four 1,000 h.p. dieselengines were fitted and gave a maximumspeed of over 8o m.p.h. Accommodationfor 5o passengers was provided.

Special precautions are necessary on thistype in order to prevent an accumulation ofan explosive mixture of hydrogen and airin the space between the gas container. andthe outer envelope. Scoops are generallyfitted which ventilate this space by means ofjets of air.

Valves are fitted at the top of the gascontainers which enable the gas to bereleased when required. To prevent exces-sive pressur! occurring, safety valves arealso fitted which operate automatically whena certain pressure is exceeded.

To enable the altitude of the airship to bevaried, - apart from operating the' usualelevator controls, water ballast is carried,with means of jettisoning in order to reducethe weight and therefore to cause the. airshipto rise. An important problem is the increaseof lift due to the consumption of fuel, etc.

Fig. 3 (Left).-Semi-rigid' keel

girder.

Fig. 4 (Right).-Rigid airship con- Control

strithion. Surfaces

After several yea's experimenting, a satis-factory material called Alclad was developed.It consists of ordinary dural with a thinlayer of aluminium on both faces to protectit against corrosion. This material is usedto -day in the manufacture of many aircraftwhose duties entail flight over the sea. In1929 the all -metal airship was constructedat Detroit in America with an Alclad skino.0095in. thick.

The capacity of this airship, known asthe ZMC2, was 200,000 cp. ft., and theprofile was maintained by means of the usuallongitudinal girders and transverse circularframes. The skin was riveted together andalmost 4,o00;000 rivets were required in theconstruction. A special tool was developedto fit these rivets which were formed fromwire approximately /32in. thick.

GasTwo alternative gases are used to provide

the lift in airship design. The mostcommonly used is hydrogen, which is the

lightest gas known. Unfortunately, it hasthe grave disadvantage of being extremelyinflammable, which offsets its advantages asregards lifting properties. Several majordisasters have been caused by airships filledwith hydrogen becoming ignited and beingentirely destroyed by fire,

As an alternative to hydrogen, helium isutilised. This gas is the second lightest gasknown, and possesses the advantage of notbeing inflammable. This last propertymakes it the ideal gas to use in airships,and the reason why it has not been generallyadopted is the fact that it is scarce. Americahas .a monopoly_in the supply of helium atthe present time, as it has not been foundpracticable to obtain commercial quantitiesin any other country.

For future airships hydrogen cannot beTransverse

Frames

ControlCabin

EnginesMounted Outside

used if the element of danger is to be reducedto a minimum, and unless some other gasis discovered, helium, which is considerablymore expensive, is the only other alternative.By using a non -inflammable gas, the enginesmay be mounted inside the hull, as in thecase of several American airships.

Ground HandlingOne of the difficulties in the operation

of large airships is the ground handling andthe mooring. Originally airships werehoused in hangars and manhandled out whenrequired. This operation 'was extremelydangerous if the wind happened to be verystrong, and a very large number of men wererequired. The introduction of the mooringmast reduced the risk of damage to theairship and rendered the handling very muchmore efficient.

A typical mooring mast of the typedeveloped in England is illustrated inFig. 5. The mast at Cardington, constructedfor the R.to I class, was 2ooft. high, and


/60 Feet

Fig. 5.=-View of a mooring mast showing 'the lift shaft.

enabled airships to moor in bad climaticconditions. A wire from the extreme noseis attached to a wire connected to a winchin the mast, which draws the airship up tothe automatic attachment consisting of aspring -loaded cup and cone. Ballast weightsare attached to the tail to prevent,excessiveswinging.' A lift runs up the mast, and agangway is fitted between the platform andthe entrance hatch in the nose,of the airship.

The smaller type of airship,i.e., the non -rigid design., isusually housed in hangars orpicketed to the ground bymeans of wire cables. In caseor an emergency, should anairship require to moor overwater, sea anchors may becarried. In addition to the seaanchor, which, is of normaldesign, an inverted cone,holding approximately half aton of water, is fixed to theline. The function of this coneis to keep the anchor submergedand to damp out any excessivemovement. To enable theanchor to be hoisted up, thewater is spilt out of the coneby means of a weight, whichruns down the line and reversesthe cone. .

The Americans have favoureda much smaller mooring mastthan the English, type. Theairship, in this case, is almost

-touching the ground, and thetail is fixed to a trolley whichis capable of rotating arounda circular track according to thedirection of the wind. A dis-advantage of this system is the

fact that extremely careful piloting is requiredwhen approaching the mast. Should therebe any vertical air currents, the airship isliable to be dashed against the ground. Theadvantage is the fact that the airship is veryaccessible for maintenance, etc.

An ingenious method of reducing the largenutnber of men normally required to takeairships in and out of their hangars is asfollows. The normal mooring mast is

mounted on wheels running on tracks lead-ing inside the hangar. By this means theairship rrTay be drawn out of its hangar quitesafely, and when outside, the mast extendsand raises it approximately too feet. As analternative to rails, caterpillar tracks may befitted to the mast, enabling it to hemante.uvred into any, position.

Future DevelopnientAn interesting achievement, with possibili-

ties for the future, is the launching ofaeroplanes or gliders from airships. Thishas already been carried out successfully inthe past, and also aeroplanes have flown upto and -been picked up by airships. On long -'distance flights, say from England to Cape -Town non-stop, gliders with mail orpassengers could be dropped at points enroute, e.g., Cairo, etc.

The possibility of propelling airships bymeans of jet propulsion is also interesting,is ther natural profile makes the fitting ofthe necessary tube more easy than in thecase -of normal aeroplanes. The developmentof a gas as light as hydrogen, withoutpossessing the danger of being inflammable,would a:so help to bring airships into theirown again.

Airships have been neglected in Englandever since the R.tor disaster, and Americaand Germany are the two main countrieslikely to proceed with the design of post-war airships. _ The German dirigibles inparticular have had an extremely ,successfulcareer, and unless some altogether newprinciple is discovered for the propulsion ofaircraft there is a distinct possibility thatairships will ' continue to be built andflown in competition with heavier-than-airaircraft.

Science Notes of theNew Victory ShipsTT is reported from America that the

Henry J. Kaiser companies will hence-forth devote their yards to the productionof two new types of vessels. The first willbe the Victory ship-biggerefaster and betterequipped than the Liberty ships, with threedecks instead of two. The second will besmall cargo vessels, about 5,000 tons, halfthe size of the Liberty ships. These cargovessels are designed to go almost anywherein the South Pacific.

Solving Air -icing Problem. .

QIR ALAN COBHAM stated in Londonrecently that experts are working on'the

problem of how to take the heat from anaeroplane engine and transfer it to the variousparts of the wings and other parts of theaircraft liable to icing. According to SirAlan, he felt sure that before long we shallhave effective de-icing apparatus.

Balloon " Scaffolding"WAREHOUSE with a circular base

A y rooft. in diameter was recently con-structed in Los Angeles by applying cementto a blown -up canvas half -sphere. Wheneverything was dry and firm the canvaswas deflated and pulled out through thedoor. There was left a smooth all -cementbuilding with no girders or columns.

New Mosquito Fighter -BomberAN improved, version of the de Flavilland

Mosquito twin-engined fighter-bomberis now in service. The new 'plane carriesa r,000lb. bomb load, and has the full fighter

armament of four zomm. cannon and four.303 machine-guns. The speed of theimproved 'machine is unaffected by the newinternal modifications, which representanother stage in the development of theaircraft like the use of wing -tip drop tanks forextra range. Improved Rolls-Royce Merlinengines give the new aircraft higher per-formance at all altitudes.

Roofing Material from RagsA CHICAGO firm has perfected a method

by which rags and resin can be com-bined to make a war -emergency buildingmaterial. Known as " corrugated asphaltsiding,' the new material replacescorrugated steel sheets. 'Fhe " siding "consists of two -sheets of heavy felt saturatedwith a resin -bituminous compound, boundtogether with a high melting -point asphaltadhesive, and then corrugated under highpressure. The finished sheets are stated tobe hard, rigid, light in weight, and moisture -proof.

First Stainless Steel AircraftTHE first large stainless steel 'plane,

described as a " twin-engined cargo -carrier of unusual construction," was recentlycompleted at Philadelphia, and passed .itstests successfully, according to the U.S. NavyDepartment, at Washington., At variousfactories itt the United States, Curtiss Wright.is beginning to manufacture cargo 'planesfor the U.S. Army on a large scale, 'andmilitary transport aircraft are being builtwhich may be a satisfactory stop -gap' forpassenger traffic after the war until newtypes can be put into production.

MonthRubber from Wild Trees

APROMISING wartime project is theattempt to tap rubber from the millions

of wild trees growing in the vast and steam-ing jungles of the Amazon basin in SouthAmerica. The U.S. Government RubberDevelopment Corporation is reported to bespending about £15,000,000 on the scheme,which may during 1944 produce 23,000 tonsof natural rubber from Brazil, Bolivia andPeru.

I.M.E. Exams in Prisoner -of -WarCamps

THE Institution of Mechanical Engineersannounces that, thanks to arrangements

made by the War Organisation of the BritishRed Cross and the Order of St. John ofJerusalem, no less than 37 candidates recentlysat for the Institution's examinations inprisoner -of -war camps in Germany. Nofewer than 34, or qz per cent., passed withan exceptionally high average percentagemarking. The results reflect credit both onthe candidafes and on members of theInstitution and others in the camps whoorganised classes and acted as instructors.

Ocean Air LinersTT is reported 'that of nine U.S. trans -

ocean± air routes proposed for after thewar seven will have their terminals inLondon. The routes were recently con-sidered by the U.S. Civil Aeronautics Board.The Pennsylvania Central Airlines propose touse a series of anchored seadromes, 800 milesapart, between Great Britain and U.S.A.

January, 1944

AIRCRAFT ON ACTIVE SERVICE


4-The Bell AiracobraBy L. H. HAYWARD

The Bell Airacobra, low wing monoplane.

THE Airacobra single seater fighter, or" Cannon on Wings," to give it thename it has earned by service pilots,

is designed and manufactured by the BellAircraft Corporation, of Buffalo, New York.The installation of the single AllisonV -1710-E4 engine in the fuselage behind thepilot, instead of in the nose, and the tricycleundercarjage place the Airacobra or, as itwas formerly called by the British, theCaribou, among the world's unorthodoxaircraft. The table below gives the leadingparticulars of the machines now in servicewith R.A.F. Fighter Command.

The front portion of the fuselage from thenose to the rear of the engine is built up ontwo main spars, while the rear portion is ofstandard monocoque construction. Thistype of construction enables a light butstrong structure to be -made, as the loadsare mostly taken by the sheet metal skin.strengthened by bulkheads and stringers. Thefront and rear portions are bolted andriveted together. Access panels are providedfor §ervicing the engine and controls. '

The all metal, full cantilever ,wings arebuilt up on two main spars, and combinemaximum strength and rigidity with mini-mum weight. The two fuel tanks havinga combined capacity of too gallons form anintegral part of the wings, which also- housethe retracted main undercarriage wheels.

Metal frames with fabric covering formthe movable surfaces of the tailplane andrudder.

The installation of the engine, in thecentre section of the fuselage, brought abouta favourable weight distribution kir fittinga tricycle undercarriage. To assist pilotsin landing on rough and strange aerodromesthis type of landing gear is fitted, as itenables an aircraft to land in a horizontal,near flying attitude at higher speeds thanthe conventional type of landing gear. Toavoid a crash in the event of -the nose wheelbeing punctured it is fitted with a special,non-skid tyre that has a dual -seal innertube. The tube has two air compartments,the inner compartment is infl4ted to a lowpressure and the outer one to the standardhigh pressure. If the casing and outer tube -

are punctured the pressure in the innersection is sufficient to expand the tube andfill out the tyre to the normal size. Theundercarriage is electrically operated, butthe pilot is provided with an emergencySpan 1 Length)f Height

34ft. I 30ft. 9ft.4in.

WeightMax. Max. I Motor I MotorLoad Speed Typo I Power

6,5001b. 400 m.p.h. Allison' 11.100Approx. v-ino- h.p.

E4

hand -operated lever enabling him to retractor lower the undercarriage wheels and flapsshould the electrical system fail.

One of the main essentials of a modernfighter aircraft is speed, and in turn thisdemand leads to larger and more powerfulengines. The installation of large enginesin the nose of an aircraft usually reducesthe pilot's visibility. To prevent this theengine is installed in the centre or largestportion of the fuselage, resulting in a

Section of thedual -seal inner

tube. ,

streamline nose giving the pilot an excellentview.

The Allison V -1710-E4, 12, cylinder,liquid cooled engine is rated at 88b h.p. at2,600 r.p.m. at sea level and 1,150 h.p. at3,000 r.p.m. at 12,000 ft. The drive fromthe engine to the reduction gear unitsituated immediately behind 'the airscrew isby means of an 8ft. long, 2}in. diameterpropeller shaft, housed in a casing passingbetween the legs of the pilot.

Ducts in the leading edge of the wings

119

"N.

lead cooling air to the engine coolant radiator -located under the -engine in the centre sectionof the fuselage, and the warm air isexhausted through an automatically operatedflap in the fuselage. The engine air intakeis situated behind the pilot's cockpit on thetop of the fuselage.

Fuel consumption of the engine isapproximately 4o gallons per hour at themaximum cruising speed of 300 m.p.h.

The British version of the Airacobra isarmed with one 2omm. cannon firingthrough the airscrew shaft, two o.5oin.calibre machine guns in the fuselage, firingthrough the airscrew blades, and fouro.3oin. calibre machine guns in the wings.In the American version zomm. cannonis exchanged for a 37mm. cannon. Thenose of the fuselage is utilised for housingthe two central machine guns and cannon,and in addition the retracted nose wheel.The guns are all aimed through a singlereflector sight and they are arranged sothat their fire is concentrated at a fixeddistance. All guns can be fired simultane-ously, or alternatively, they can be selectedto fire individually.

Electrically -heated clothing and oxygen'equipment for the pilot are provided forhigh altitude operation. A specially designedcrash arch protects the pilot's body inthe event of a crash landing, and a bullet-proof windscreen protects him from enemybullets. The normal range is approximate:y75o miles, and this is found to be amplefor most combat flights.

The Airacobra is one of the very fewaircraft that can claim the distinction ofhaving a span of almost the same length asthe fuselage. The prototype machine madeits first appearance towards the end of 1938,and since then very large numbers havebeen put in service by the R.A.F. FighterCommand and the United States Army AirCorps. Due to the location of the enginenear the aircraft centre of gravity, a muchlarger degree of manoeuvrability is obtained.

One of the most unorthodox aircraftin the world, with a speedapproaching 375 m.p.h., itcertainly deserves the name" The Cannon on Wings."

Extension Shaft.

The 8ft. extension shaft fitted to the Allison engine installed inthe Bell Airacobra.


Penicillin, the New Germ KillerChemistry's Latest Contribution to the Battle Against Bacteria

NOT all bacteria or germs are harmfulto human life. On the contrary,quite a number of these microscopic

living entities are definitely beneficial to ourhealth and well-being. Nevertheless, therelatively few species of antagonistic germs-the " pathogenic bacteria," as they arecalled-which war against human and animalhealth and even life itself can, given favour-able conditions, become extremely potent,speedy and deadly in their capabilities.

In olden times before the introductionof chloroform apd other anaesthetics, it wasnot so much an actual surgical operationwhich was so greatly dreaded both by patientand surgeon alike as the onset of the fear-some and frequently fatal gangrene ormortification of the bodily tissues after theoperation.

It was not, indeed, until after- the middleof the last century that the true nature ofsurgical gangrene began to dawn uponscientific minds. That great French geniusand medical pioneer, Louis Pasteur, had"hown that many diseases and bodily con-ditions are due to the activities of tinycellular or plant -like parasitical bodies, nowa-days popularly called " germs," and inconsequence of this realisation it becameapparent that one of the obvious ways ofdealin with these microscopic foes would beto apply to them some chemical substancewhich would not only destroy them butwhich would also prevent their regrowth.

From such considerations arose graduallythe present-day practical science of " chemo-therapy," the science, as we may define it, ofdisease treatment by chemical means.Chemotherapy, in our days, has developedinto a highly complex, albeit ultra -fascinating and many -branched departmentof -organic chemistry, of which, in thisneces-sarily brief survey of the subject, we can onlydeal with one small portion, to wit, thatconcerning the discovery and developmentof chemical aids to germ destruction.

The First AntisepticIt was Lord Lister, one of the more famous

of British surgeons, who in 1867 first intro-duced as aids to surgical operations sub-stances which he termed " antiseptics," thatis, substances which inhibit or prevent thedevelopment of sepsis or mortification of the

bodily tissues caused through germ action.Lister tried to use carbolic acid, which was

the pioneer antiseptic, but although thecarbolic acid killed the unwanted germs it

Lister, English surgeon and pioneerof antiseptics and germ -killers.

also acted detrimentally upon the patients'wounds and tissues, for it functioned as apoison to the living cells of the flesh as wellas to the pathogenic bacteria. Carbolic acid,creosote and guaiacol were used in verydilute solutions as antiseptics, and variousother synthetic compounds were added tothe list of antiseptic substances as time wenton. Some of them were more successful than. others. But they all had this real dis-advantage ; they could not be taken internallyor injected directly into the blood stream inorder to kill germs which had gained a firmhold on some inner organ of the body. Youcould not, for instance, allow a patient todrink carbolic in order to cure hispneumonia, because if you adopted this

Lord

Cultures of penicillium patulum of Agar medium.

course of action, although you might succeedin killing the pneumonia germs you wouldalmost certainly have to attend a coroner's inquest over the death of the patient!

Antiseptics and other chemical germ -killers were all very well in their respectiveways at this stage of chemical science, butthey were not selective enough in action.They tended to destroy both the living germsand the living cells of the body.

Next came Paul Ehrlich, a German investi-gator, who, in 5904, discovered that a certaindyestuff, uypan red, possessed the propertyof killing certain disease organisms calledtrypanosomes which are- responsible forcertain tropical diseases.

But Paul Ehrlich went further than this.He conceived the idea of chemically syn-thesising a substance which would be ableto act on bodily disease germs as a sort ofpoisoned arrow, carrying its dose of poisonto the germ which it was aimed at andthereafter becoming harmless to the restof the body.

Ehrlich selected the Well-defined spirillaor corkscrew -like germs -of syphilis for his

A close-up view of Penicillin mould growing ona gelatine medium. It is from this mould thatthe new antiseptic, penicillin, is being obtained.

experiments. He built up synthetically inhis laboratory compounds which containedarsenic in loose combination. His idea wasthat if he injected his new selective germ -killers into the blood of patients sufferingfrom syphilis, the chemical would unloadits cargo of arsenic on to the spirilla of thedisease and so cure the patient.

After a good deal of patient experimenting,together with no small amount of failures,Ehrlich succeeded rather spectacularly in hisquest. The result was his selective germ -killer which he named " Salvarsan " andwhich formed the' first of a group ofarsenical compounds used for similarpurposes.

Selective Germ -killer _

Salvarssn introduced an entirely newprinciple into chemical medicine, theprinciple of the selective antiseptic. Duringthe last war, it was found that several dye-stuffsi notably acriflavine, had powerfulgerm -killing properties, whilst being, at thesame time, harmless to the body. Suchantiseptics were used in large quantities

Januafy, 1944 NEWNES PRACTICAL MECHANICS 121

during the 1914-18 war, and undoubtedlysaved many thousands of lives.

Within the last ten years, the work ofEhrlich and other contemporary pioneershas fructified in the new era of antisepticand germ -killing compounds which is nowrapidly dawning upon us.

It is not very long since two new classesof bactericides (germ -killers) were placedon the market. Such drugs are now typifiedby the substances " Prontosil ". and" M. & B. 693." Plontosil is, in reality, adyestuff. It is predominantly destructive ofgerms belonging to the group known as thestreptococci:. And because it is this groupof germs which is very much concerned inthat once -dreaded puerperal fever (the feverof childbirth), prentosil made its name asa saver of many lives.

Then, shortly afterwards, were syn-' thesised the first of the "M. & B." (May

and Baker) bactericides, which are, inparticular, specific against the deadlypneumococci, the germs responsible forpneumonia. Such compounds containsulphur in organic combination. Hencethese substances are chemically known asthe " sulphonamides." Many hundreds ofthem have been synthesised, but only arelatively few are used in ordinary medicalpractice.

PenicillinThe most recent developfnent in the crea-

tion of super -power antiseptics and germ -killers is to be seen in the discovery of thenew chemical, penicillin, which isnow beingproduced on the commercial scale.

The story of penicillin is an interesting

A microscope view of Aspergillus, the greenmould of cheese. From this mould the new

antiseptic fum igatin is obtained.

one, not only in view of the rather strangeorigin of this new compound but, also,because its introduction to medicine opens -out further fields of discovery for theenthusiastic and highly skilled chemicalworker.

It is a well-known fact that nearly everyvegetable material is, under favourable con-ditions, liable to become attacked byvarious moulds which grow parasiticallyupon it. Fruits, cheese, bread, jams, sugarsolutions, fabrics, wood and a host of otherdivers materials will all go mouldy whenexposed to the right conditions.

Moulds, of course, are merely forms ofplant life which exist upon the nutrimentwhich they abstract from the materials uponwhich they grow. Given moisture, -air, alittle light and a suitable medium in or onwhich to grow, the majority of them flourishexceedingly.

One of the commonest of the everydaymoulds has long been given the name ofpenicillium (Latin, penicillum, " a brush ora pencil ") in allusion to the long, thin,

- brush -like filaments which it manifests whenviewed under the microscope. The variousspecies -of penicillium moulds are very de-structive. It has been estimated, forexample, that, in pre-war days, penicilliummoulds attacking packed fruit accounted for

2-3 per cent. loss on fruit imports intothis country, amounting annually to somemillions of cases of fruit. Yet, by a curious

Chromotographic columns of a simple type forlaboratory use. They consist of glass cylindersfilled with aluminihm oxide through which mixedsolutions are percolated in order to effect theirpurification and separation, as in the case of

penicillin extracts.

twist of coincidence, it is from this very`group of penicillium moulds that the mostup-to-date and probably the most powerfulof all the known bactericides or germ -killersis now being manufactured.

A Product of Mould GrowthThe discovery of penicillin, the new

bactericide, came about in this way:In 1929, Professor Alexander Fleming, of

St. Mary's Hospital, London, noticed thatone of his bacteria culture media refusedto grow the germs which he required. Heinvestigated the matter and found that thisparticular culture -medium had gone slightlymouldy, having become, through an accident,infected with the mould, penicillium, one ofthe common green moulds.

Professor Fleming's curiosity was aroused.He purposely grew a quantity of thepenicillium mould. Then he inoculated somegerm cultures with extracts made from themedium in which the mould had grown.The result was that the germs refused togrow in their various media and that, insome instances, they were actually destro)red.

It became obvious that the extract of themedium in which the penicillium mould hadbeen grown contained some substance whichexerted a powerful antiseptic effect uponcertain types of bacteria. To this mysterioussubstance the name " penicillin " was given,although its chemical nature was at thattime entirely unknown.

Although some investigational work onthe chemical ¢roducts of mould growth hadbeen done previous to Professor Fleming'sdiscovery, surprisingly little was known tenyears ago about these products: The 'Flemingdiscovery, however, gave a fillip to chemicalresearch in this direction, and a number ofinvestigators got td work 'without delay. Workon this subject is still proceeding, and evenwithin a few short years, several new com-pounds derived from the growth of commonmoulds have been discovered, the majorityof which are highly antibacterial in nature.

There is no doubt at the present juncturethat penicillin is by far the most powerfulof these new bactericides. It has beenproved to be an extremely potent antiseptic.A soluti9n containing 1 part of penicillin in25 million parts of water has a strongbactericidal action. Helve, penicillin is farmore powerful than even pure carbolic acid.

The great advantage of penicillin as agerm -killing agent is that its action is quiteunaffected by ,the presence of blood, serum,mucus or pus. Moreover, it is non-poisonousto humans. It can be injected directly intothe blood stream without ill effect. Conse-quently an injection of penicillin given afteran individual has received any bodily injurywill go far towards completely preventingthe appearance of any sepsis or mortificat on.

In the incubator room showing cultures of the mould, one of the penicillium series, inflasks. Numerous series of moulds are grown for testing for anti -bacterial activity.


That is why penicillin is in such demandamong the modern armies as an almostcertain life-saver. Apart from this use,however, it is very possible that penicillinor, at least, other compounds of its class,will figure largely in diminishing the futuremortality rates of many other civil -lifediseases, the various fevers, for instance, tosay nothing of the present-day often

Laboratory culttires of moulds used for reseathe investigation of the new mould -made

ineradicable bronchitis and similar chroniccomplaints.

Chromotographic SeparationPenicillin has not yet been synthesised or

created artificially. Its precise chemicalcomposition is not yet known, and untilsuch details are available its synthesis willremain impossible.

Owing to the fact that penicillin is onlyproduced in small amount by the mouldpenicillium and that it is somewhat liableto become oxidised, this new substance isvery difficult to manufacture on the commer-cial scale. Its manufacture, however, isbeing tackled in America by dint of extract-ing mould. cultures with a mixture of amylacetate and water. The mixture is thensubjected to the new technique of chromoto-graphic separation, which latter, in itsessentials, consists of allowing the mixtureto percolate through a column containingsome absorbent material such as aluminiumoxide. It is found that, by this means, onecomponent of a mixture is absorbed by the

. aluminium oxide at the top of the columnwhilst another component will be absorbedand retained lower down. By dissolving outthe various " bands " or areas of thechromotographic column with suitablesolvents a fairly good separation of complexmixtures can be achieved.

It is, therefore, by this new chromoto-graphic method that all penicillin extractsare purified. No doubt, after the truecomposition of this remarkable compound isclearly known, it will become possible tomanufacture the material in much largeramounts and by far more convenient andspeedier methods. At the present, however,penicillin production is one of the mosttedious of processes in chemical industry,yet so valuable is this novel material thatit is being eagerly sought after by medicalscience the world over.

NotatinAnother ultra -powerful antibacterial sub-

stance has 'been recently' isolated from mediain which the mould penicillium notatum hasbeen grown. To this new material thename of "Notatin " has been given.Whether notatin is a mixture of penicillinand some other unknown substance, orwhether it is a single chemical compound,is not yet known. One thing, however, iscertain. Notatin is capable of stoppingbacterial growth in dilution as high as onepart of notatin in one billion parts of water.Notatin seems to be more stable than

*penicillin, and if it is a pure substance itmust also be considerably more powerfulin its antibacterial activity than the latter.

Within the last year or two, other mould -grown chemical materials have been broughtto light and examined. Without exceptionthese have all shown_themselves to be highlybactericidal in properties. Puberulic acid,puberulonic acid, penicillic acid and

citrinin are but four ofthese newly revealed anti-bacterial compounds.These are not so potent aspenicillin itself, but theyseem to be much morereadily obtained, particu-larly the compound,citrinin.

The value of these lattersubstances lies in the factthat the chemical structureof them is now known withsome degree of certainty.This being the case, theymay in all probability be

rch purposes in made to act as " models "antiseptics. upon whose structural

design the creation andsynthesis of other and morepotent antibacterial com-pounds may be based.

Spinulosin and Fumi-gatinTwo more interesting

" mould compounds " arespinulosin (made from themould, penicillium spinu-losum) and fumigatin (de-rived . from Aspergillusfumigatus, an entirelydifferent type of mould).Both spinulosin and fumi-gatin have been success-fully analysed and synthe-sised. Whilst spinulosin isonly a relatively weak bac-tericide, fumigatin haspowerful antibacterial -properties against the bac-teria of anthrax andcholera. As in the case ofthe previously mentionedsubstances, both spinulosinand fumigatin -will prob-ably . function as models for the artificialcreation of other compounds of greater

potency by future chemical researchers.The majority of the new antibacterials,

when they have been obtained in pure form,have shown themselves to be solid, stronglycrystalline substances which are soluble inwater and various other liquids. Most ofthem are colourless, but a few, notablyspinulosin and fumigatin, are coloured.Thus, for instance, spinulosin takes the form,when pure, of purplish -brown crystals,whilst fumigatin is maroon coloured.

It is with these new compounds preparedfrom common moulds that the baCtericidalbranch of chemotherapy is at present achiev-ing its almost spectacular successes. Fromcomprising the out-of-the-way researchsubject of a few isolated chemical enthusi-asts, mould chemistry has suddenly becomea commercial proposition, and is, at thepresent moment, being prosecuted assidu-ously in that direction, for, with thesestrange and peculiar mould -made com-pounds it seems likely that the ideal of thatintrepid pioneer, Paul Ehrlich, may yet bereached and that selective antibacterialsubstances will be discovered which,whilst being deadly to their ownparticular strains of gertns, will be perfectly

The new technique of injecting harmless germ -killers andantiseptics directly into the blood of a patient in order toovercome the danger of infection from accidental injuries

. and wounds.

innocuous to all forms of human and animallife.

An Aid toAVERY useful and ingenious addition to

rapid Calculation equipment has justbeen introduced by W. J. Steel and Co.,Lid., of Bedfont, Middlesex. It is registeredas the " Confractor " and is a most compactconversion table of inches to millimetres andvice -versa, covering a range from 1/128 partof an inch to .6 15/16 inches and one totoo millimetres. The " Contractor com-prises three discs each about 1/32 inch thickmade from an almost indestructible plasticmaterial and the discs are fastened togetherin the centre with a brass eyelet so thatthey rotate upon each other. A slot isarranged on the left hand side of. each outerdisc, . to reveal the figures boldly printedupon each side of the middle disc and thedevised conversion is obtained by simplyrotating the disc. The range of conversiondata provided is upon the following generousscale :

(A) Inches to Millimetres (to seven decimalplaces)Reading through the slot on one side of

the " Confractor " the table grottos theconversion in 1, 1, /t6, 1/32 and 1/64inch stages and 'at the same time gives

Efficiencythe equivalent of the fractions to sixplaces of decimals.

(B) Inches to Millimetres (to seven decimalplaces)Reading through the slot on the opposite

side of the " confractor " the odd numera-tors of 128th parts of an inch are con-verted to millimetres and the equivalentof the fractions to' seven decimal placesare also given.

(C) Inches to MillimetresReading on the surface of one outgr

disc the millimetres equivalents are tabu-lated to two decimal places from r inchin stages of 1/ t6th inch up to 6 5/16thinch.

(D) Millimetres to InchesOn the surface of the other outer disc

the inch equivalents to five decimal placesof one to fifty millimetres is given pro-gressively and then in stages of five up toone hundred millimetres.The " Confractor " is being distributed

solely by the above firm at the reasonableprice of 4s. 6d.

January,. 1944 NEWNES PRACTICAL MECHANICS 12.3

-V

EnAineer-built Houses of*ZM:i Igr-mt ture-12 (Continued fromFu agcepsi

Party Wall Construction -,-Solid

Party Wall and Fireplace ConstructionTHERE are three rather important

differences between party walls,which. divide two houses, and external

walls: (I) a party wall requires a higherdegree of acoustical insulation than, an,external wall because of the need to prevent'all normal sounds from one house beingtransmitted to the adjoining one ; (2) aparty wall needs to be more reasonably fire-resistant than an external wall ; and (3)although a party wall can be designed totake a good proportion of floor and roofloads, more often than not the majority ofsuch loads aFe borne by external walls andinternal partitions-there is often a tempta-tion to the structural designer to avoidletting floor units bear on party walls unlessthe method of construction is such as willensure reasonable immunity of sound trans-mission, to the adjoining house, and firerisks in the case of floors built with timber.A study of the general structure of a pairof semi-detached houses will show (a) thata party wall having no fireplaces in it, and

Fig. 64

Fig. 67

Fuel, Gas and Electric FiresWiles of Jerry Builders

By R. V. BOUGHTON, A.I.Struct.E.

not having any or mud; lateral support by,say, a first floor being adequately securedto it, can have a very high slenderness ratiobetween its base and roof level ; it is quiteprobable, in the case of a two -storey house,that the height, of the wall will be about18ft., and if the wall Is only 6in. thick, theslenderness ratio will be t8ft: divided bylit. equals 36, which is far too great.Therefore it is essential that if adequatelateral support' is not provided by the first -floor construction bearing on and beingproperly connected to a party wall, meansmust be adopted to ensure a degree of unitybetween the wall and floor units so thatadequate lateral support is provided. If theSide of a floor unit is parallel to the lengthof a party wall, and the unit is rigid, itis only necessary to tie the side of the unitto the wall to make certain that. lateralsupport is provided ; and the tying may bedone effectually by stout metal clips well

Fig. 68

Fig: 65

+0-

in Pre -built Houses : The

screwed to the floor units and bedded andfixed to the party wall units ; (b) that aparty wall having solid fuel (coal, coke, etc.)fireplaces constructed in conjunction with it ;such fireplaces having breasts which pro-ject beyond the faces of the party wall willconsiderably strengthen the wall by stronglybuttressing it. Although pang of the partywall between external walls, partitions andfireplaces are not actually buttressed, theyare, however, of short length ; by this ismeant that such parts of the party wall maybe considered as Only governed by a hori-zontal ratio of slenderness based on thedistance between the external walls, partitionsand fireplaces.

Before considering the construction ofparty walls and fireplaces of engineer -pre-built houses, I recommend a careful studyof traditional -methods of brick party walland fireplace construction as shown by Figs.64 and 65. Notice theconsiderable amountof brickwork in thefireplaces and breast s-

Fig. 69

-H

z-.

Fig. 66

Figs. 64 and 65.-Traditional methods of constructing brick party wall and fireplaces, etc. Fig. 64 is ground storey and Fig. 65 is first storeyconstruction. A-Party wall. B-Fireplace jamb. C-Fireplace opening and back hearth. D ---gin. thick brick ,back. E-Front hearth.F-8in. by 8in. flue. G -4 -4 -in. thick brickwork. H-Parging.Fig. 66.-Plan of party wall and fireplace in ground storey of engineer -built -house. A-Concrete pre -built party wall units. .11-Insulated wallcovering or finish. C-4+in. thick brick (or concrete) fireplace jamb. D-4iin. thick brick fireplace back. E-Solid fuel (cod., coke, etc.) fire-place opening. F-External wall. G-Firebrick back. H-Fine concrete. 1-Surround.Fig. 67.-Plair of fireplace just over fireplace opening. A-Party wall. B-Jamb. C-Base of flue. D-Throat to fireplace. 4-FireplaCeback. F-Concrete lintol.Fig. 68.-Plan of fireplace at shelf level. A-Party wall. B-Yamb. C-Fireplace back. D-Flue of metal construction with exposed faceslined with metal or other material to suit cesthetic requirements and to make the exposed faces as flat heat radiators. E-Shelf.Fig. 69.-Plan of fireplace in first storey. A-Party wall. B-Jamb. C-Fireplace back. D-Flue as Before described from ground storey fire.E-Solid flue fireplace opening. As this opening is comparatively small and suitable for a small fire, it may be used for a gas fire. F-Upper partof fireplace opening joined to suit type of fire used. G-Flue over. H-Front hearth.

124 `NEWNES PRACTICAL MECHANICS January, 1944the width and projection into the rooms-and, if the sizes of concrete bases and stacksin and above roof are borne in mind, itmay be evident that this traditional, heavyand really wasteful method of constructioncan be' superseded by much better, lighterand more economical (if all direct andindirect advantages are analysed) methodsof design and construction. I am aware ofthe essentials which govern fire -resistance,upward draughts, and other vital codes ofpractice of fireplace, etc., design, but I amalso aware that all these essentials can bemet by adoption of better methods-manynew, at least as far as this country is con-cerned, but which in some cases accord togeneral principles which have been usedsuccessfully in other countries.

'Fig. 7o.

5

A

C

L

F

N

Fig. 66 depicts part of the length of aparty wall between two houses and a groundstorey fireplace for solid fuel. It is inter-esting to note the great difference in theamount of brickwork-or it may be concretework-in the two 'methods of constructionshown by Figs. 64 and 66.

Pre -built Party Wall ConstructionThere is a school of thought which advo-

cates traditional methods of construction forparty walls of pre -built houses-viz., the useof brickwork. The reasons advanced arethat brickwork is fire -resisting, it allows forthe comparatively easy construction of fire-places, etc., and, if well built, is a reasonableinsulator against sound. These reasons havea good foundation of common sense ; but

Fig. 71. Fig. 72.

o

against them modernists offer the followingcontributions on behalf of the bettermentof building: (r) that concrete, and reinforcedconcrete, may be comparatively thin com-pared with brickwork and therefore savespace, weight, and, what is by no meansunimportant, an appreciable reduction inbase and foundation work ; (2) that concrete,and reinforced, concrete, can be pre -built(brickwork cannot), and (3) they can becombined with sound insulating sheetmaterial to ensure a thin wall being satis-factorily fire-resistant, proof against normalnoises, and can be covered with any of thevarious classes of wall boards.

Figs. 66 and 7o show the use of i8in.-widereinforced concrete units covered withinsulating material and wall boards. The

a

2. Fr

F

I '

SECTION Y -Y SFeCTION Z. - z, E-1-E_VAT ONFig. 70.-Section through party wall shown by Fig. 66. A-Concrete pre -built party wall units. B-Insulated wall covering oi finish with hollowspace behind. ,C-Insulated wall covering or finish applied to solid part of concrete units. D-First floor. E-Side of fireplace. F-Ground floor.Fig. 7t. -Sec ton through fireplaces and chimney breast shown in plan by Figs. 66 and 69. A-Fireplace back. 13-Fireplace opening. G-Surround., D-Structural concrete slab over opening with aperture to take metal throat of flue. E-Concrete (or other material) shelf. F-Metalflue and radiator as before described. G-Face of flue. H-First floor and hearth. J-Side of flue. K-Concrete lintol. L-Firebrick back.M-Fine concrete filling. N-Flue shaped to form throat over fireplace opening. 0-Shelf in distance. P-Ground floor.Fig. 72.-Elevation of fireplaces and space -saving flue and breast construction. A-Fireplace openings. B-Tiled or sheet material surround toopening. 7-Electric fire. D-Shelf. E-Brick (or concrete) jamb. This may be omitted if desired and is not required for any superstructure.F-Face of flue. G-Twin flues. brick jamb can be built here if desired for any structural purpose.Fig. 73.-Plans of party wall with gas fire openings and ,flues: 1-Ground floor level. z-Gas fire flues in ground storey. 3-First floor level.A-Pre-built party wall units. B-Gas fire openings. C-Gas fire. D-Flue blocks.

January, 1944

design allows- that the first floor will pro-,vide adequate lateral support to the partywall at first -floor level, and, even if therewas no fireplace construction, structuralstability will be ensured. Another methodis to include a beam at first -floor levelrunning in the direction of the length of theparty wall, Such beam making the effectiveheight of the wall units about 8ft., and ifthey are 6in. thick the slenderness ratiowould be 16, which is quite good. If theparty wall contains fireplaces, they formexcellent buttresses and also bearings forany beams used in the party wall. Thereare, of course, several types of party wallunits which may be used in lieu of thoseshown, and according to structural require-ments they may have their lengths eitherhorizontal or vertical.

Solid Fuel Fireplace ConstructionWe have become too accustomed to

orthodox or traditional methods of structuraland xsthetical design of fireplaces, and Iam a strong believer that the public- areonly too willing to accept any modernmethods which can be proved to be betterthan those which our ancestors gave us. Thepublic are becoming used to electric andgas fires but it is generally accepted thatthey really do like one or two coal or solidfuel fires in a house, and, consequently, itis advisable that designers of pre -builthouses be prepared to cater for this liking.


symmetry. In my view space should be ofutilitarian value, and I suggest that the spaceto the.left of the flue constructioan as Fig. 72is much more useful for shelves, etc., thanif it is blocked in with a useless mass ofconstruction simply for the purpose ofproviding what some consider goodappearance."

In connection with the general principlesof fireplace construction which I advocate,a few points of interest and importance maybe now considered. The use of brickworkdoes mean " wet -construction " on site,which pre -building principles endeavour toavoid as much as possible ; but in thisrespect it should be granted that " wet -construction," if it is for ,the betterment ofbuilding; should not be discarded. If thedesigns are studied it will be apparent' thatvery little brickwork is incorporated : thereis no heavy work, and no wasteful founda-tions, because the lightness of the construc-tion makes it practicable to build thebrickwork directly on the concrete floor oron a very simple and small concrete base; mostof the brickwork can be, built withoutscaffolding, and that above " firstscaffold height "--5ft.-can bebuilt off trestles. *Although I haveshown by thevarious illustra-tions, and which isparticularly e v i -dericed by Fig.72, a half -brick -thick jamb to the

125 -

Gas and Electric FiresGas fires require small flues to carry off

the fumes, and Fig. 73 shows how thesemay be incorporated in party walls, and verysimilarly in external walls. Manifestly, thetype of construction provides practically nobuttressing effect to walls.

The Wiles of Jerry BuildersFig. 74 shows a typical part section

through a timber house 'roof-a type of con-struction - which can be seen in manyhundreds of thousands of roofs to houses.In fairness to jerry builders, I must statethat unless they have a knowledge equal tothat of a first -year student of elementarybuilding construction they are not entirelyto blame for constructing house roofs whichgenerally foul the most -elementary canonsof decent construction and the laws ofmechanics of structures. An examination ofthe timber members of a vast majorityof the roofs over, houses will provide evidencethat rafters and purlins usually conform toby-law requirements, and struts,. which areexceedingly important members, and are not

LI-E-VATION Y -YBEARINGS FOR

FEZT OF STRUTS

k? -1

F_LEVATION 2.-2.

-IT I U

PLAN OF BINDER LTC.Fig. 74.7 -Part section of a typical jerky -built roof. A-Common rafters. B-Perlin.' C-Strut usually of ill-considered size, shape, etc. D-" Binder," viz., a length of Sin. or 4in. by 2in. timber laid across top of weak ceiling joists, the binder and joists being nailed together.' The objectof this form of construction is to prevent the ceiling joists twisting, to assist in distributing any point loads over several joists, and does little to preventthe 4in. by 2in. ceiling joists, which usually span twice the distance they should, sagging and cracking the plastered ceiling. F-4in. by 2in. ceilingjoists. G-Plastered ceiling.Fig. 75.-How a house roof should be constructed (engineer pre -building allows for entirely different methods of construction). A-Purlin. B --Packing. C-Nailed joint -2 nails each side. D-fin. bolts. E-3in. by 2in. tension plate which being birdsmouthed with common rafters andnotched into ceiling joists, provides strong resistance to thrust of rafters and pull of joists. F-Common rafters subject to compression and bendingstresses. G-Ceiling joists which may be of small size, such as 3in., 3iin. or, 4in. by 2in., depending on their span between binder and other ceilingjoists sagging. I-Binder in plan. K.-Nailed joist. L-W.I. straps which form a joint between ceiling joists and binder, which is as strong as themembers they connect.N.B.-This method of construction is intended to conform with the good L.C.C. by -jaws for timber construction which are followed by many localauthorities outside London area. These by-laws require ceiling joists to be of about the same size as floor joists for cThmestic buildings.

But, in such catering, it is just to concludethat much saner methods than those whichhave prevailed for hundreds of years cannow be adopted in view of what modernscience has taught, is teaching, and willteach us. A very high percentage of theheat of an ordinary coal or coke fire goesup the chimney and is completely lost --completely lost and wasted, unless it canbe argued that a little heat is given offfrom a flue which passes through a wallof a room. Subject to ensuring sufficientdraught up a flue, and prevention of down -draught, it is practicable to utilise much ofthe heat which goes up a flue for heatingspecially and simply constructed panelsadjacent to the actual flue, or, in other words,not to use' thick brickwork for .surroundinga flue, but, instead, to use metal in the formof a flat radiator: This method of flueconstruction is in principle shown by Figs.67 to 69 and 71 to 72. It will be noticedthat the structural design eliminates allforms of construction used merely to givewhat may be termed xsthetical balance and

side of the flue, extending the full storeyheight, this jamb can be omitted. But itmust be realised that such jambs are some-times necessary to assist in supporting thefireplace work in the storey above if thereis no solid foundation, such as a concretefloor, to provide support. Cast iron or sheetmetal flue pipes are a practical proposition,and they can be treated so as to radiate heator be insulated against heat when adjacentto inflammable material. Initially, they maybe rather costly ; but against this cost mustbe set many direct and indirect savings, suchas reduction in brickwork and other tradi-tional structural work, and heat -conservingpowers. If all these considerations areanalysed in a financial light, it will be foundthat the advocated modern methods will becheaper than the old heavy type of brickfireplace construction depicted by Figs. 64and 65.

I have for 'a good reason not shown howthe fireplace construction may terminate atroof level in various ways ; these dependon the type of roof,

adequately regulated, as to size by the pre-1939 by-laws, are usually of wrong design.Joints, which should be at least as strongas the members which they connect, are notstrong enough, and often ill -constructed.Ceiling joists, usually 4in. x 2in., spanridiculously too long spans and consequentlydeflect and cause plastered ceilings to crackand look like an inverted undulated countryscene and that such weak ceiling joists aresupposed to be strengthened by " binders,"which are bits of timber placed across thetop of, and nailed to, the ceiling joists, whichare viewed by structural engineers with thesame contempt as a modern mother doesthe use of binders-a ,few yards of super -wide tape into which a baby isienveloped onthe rolling -pin method.

The construction of many roofs over jerry-built houses is really appalling-good andvaluable material mostly wasted, as far asstrength is concerned, by designing and con-structing without knowledge of even theelementary laws of construction.

(To be continued )


The Story of Chemical Discovery

The Chemistry of CombustionUnderlying Features of Fire and Flame

THE circumstances under which fire, andflame, those twin chemicalphenomena, were first brought to the

notice of mankind have many times beenspeculated unon. ,The truth is, of course,that we have no idea of -how man firstbecame practically acquainted with the uses

double -cylinder air -pump, such as waspioneer experiments on the nature of

combustion.

of fire. Such an acquaintance may havebeen consequent noon a lightning storm, avolcanic eruption, the natural heat of thesun's rays, frictional effects, or even uponsome untoward incident of spontaneouscombustion. All we know is that mankindmade practical use Of fire and combnstionat a very early period of its history, and,without any doubt, man's continued usageof fire and flame underlies a very greatproportion of his truly remarkablecommand over Nature.

Fire and flame are inherently chemicalprocesses and chemical effects. Yet theywere known and made use of for unknownthousands of years before their real naturefirst dawned upon human reason. Puttingaside the ancient pseudo -scientific' philoso-phers who at times speculated wildly andalmost fantastically on the nature of, fireand flame, the first man to put onrecord a reasonable observation concerningcombustion was that great and many-sidedItalian genius, Leonardo da Vinci, who,towards the end of the sixteenth century,noted down in his writings the fact that airis necessary fiipthe maintenance Of the flameof a burning candle. Our English philoso-pher, Robert Boyle, one of the first membersof the English Royal Society, noticed, in1661, that a flame would -go out for " wantof air." He perfoimed several experimentswith his newly -devised air pumps by meansof Which he gradually pumped out the airfrom a glass vessel containing a burning

candle. Invariably the flame of the candlewas extinguished after a certain proportionof the air had been withdrawn from thevessel.

Robert Boyle definitely proved that airis necessary for flame and combustion. Also,a most significant suggestion was thrown outby his brilliant contemporary, the curious,crotchety Dr. Robert Hooke, first secretaryof the Royal Society in Charles II's time.Hooke threw out the idea that ordinary aircontains a substance " which is like, if notidentical with, that which is fixed insaltpetre."

Lightning has been credited withbeing the, first fire -giver to mankind.This photograph of a single light-ning flash was taken on a summer's

night in Manchester.

We know nowadays howaccurate old Robert Hookewas, for air contains oxygen,and so does saltpetre (potassiumnitrate), a fact which enablesthe latter to play its well-knownpart in the production of gun-powder, and other highly com-bustible and explosive mixtures.

Mayow's EiperimentThen, about the year 1674,

came John Mayow, an Englishphysician, who devised anexperiment in which a -candlewas burned in a confined spaceover water.- After a time thecandle flame, went out and thewater -level rose in the enclos-ing vessel. Although thecandle - flame had been ex-tinguished, some- gas remainedin the enclosing vessel or jar.Hence, Mayow concluded thatair contains two substances cr

Particles," as he termed them,the "-nitro - aerial particles "which were withdrawn fromthe air during the burning of

the candle and the ordinary " aerialparticles " which had nothing to do withthe burning and which were left behindin the jar.

Mayow showed, also, that a similar effecthappened when, instead of a burning candle,a live mouse was confined in a jar of airstanding over water. The water graduallyrose in the vessel and eventually the mousedied, proving thereby that during itsbreathing it had abstracted from theenclosed volume of air the same activeprinciple which the burning candle hadmade use ,of.

John Mayow was on the very brink of thetrue and rational explanation of flame andcombustion. For all that, he missed suchan explanation of the -revealed facts, mainlybecause the chemical science of his day wasso extremely immature and fragmentary.

In the eighteenth century, the experi-ments of Mayow became forgotten. ' The" phlogiston " theory of heat and com-bustion arose and held the day . for manyyears until it was finally vanquished by thediscovery of oxygen and the recognition of -its true part in the phenomenon ofcombustion.

The phlogiston theory has previously beendescribed in this series of articles. For thebenefit of the new reader, however, it maybe stated briefly that " phlogiston " (from

An electrical apparatus for determining the precise ignitiontemperatures of gases and vapours. The gas is stored inthe small gasholder shown in the foreground. It is thenallowed to flow into the tall cylindrical electric furnace behindthe gasholder, in which chamber the, temperature of itsignition is electrically recorded. (Prof. H. B. Dixon's

apparatus-University of Manchester.)


A modern reproduction of Mahow's experimenton the burning of a candle in an enclosed space

above water.

the Greek, phlogisteo, "I set on fire ") wasconsidered to be a very mysterious, im-ponderable, invisible and even a weightlesssubstance which was a constituent of allcombustible materials. When a combustiblesubstance was burned, its stock of phlogistonescaped from it, either wholly or in part.Fire, flame and combustion, therefore, weremerely phenomena connected with theescape of this remarkably tenuous and,indeed, truly ' fantastic substance orprinciple, " phlogiston."

"Last of the Phlogistonists"Right - through the not inconsiderable

chemical development of the eighteenthcentury, the phlogiston theory of fire andcombustion held the field. Even the Rev.Joseph Priestley, the Yorkshire dissentingcleric who discovered the gas which wenowadays call " oxygen," fanatically clungto and . defended the phlogiston theory tothe very end of his life, a fact which hasgained for ithis worthy individual the some-what dubious title of " the last of thephlogistonists."

It was the great Antoine Lavoisier(1743-94), the politician -chemist who wasexecuted during the French Revolution, whofounded our modern theory of combustion.This he did merely by replacing " phlo-giston," by oxygen. In consequence of thecareful work of Lavoisier and others,chemists came to realise that oxygen, theever-present constituent of the air, is theuniversal supporter of both animal life andcombustion. When a substance burns Itabstracts oxygen from the air. When ananimal breathes, it does the same thing.Burning and breathing are merely twodifferent aspects of the same thitql; they areboth oxygen -using processes.

How near had old. John "Mayow been tothe truth nearly a century before Priestley,Lavoisier and their contehiporary workerswere ever thought of !

A

The principle on which the miner's safety lamp is based. Sketch Adepicts the flame of a bunscn burner igniting above the wire gauge. AtB the flame is shown burning below the gauze ; in both instances thecooling effect of the gauze prevents the.upward or downward spread of

the flame.

Lavoisier founded ' our present-dayknowledge of fire, flame and combustion,but he did not live long enough to delveinto any great semblance of detail concern-ing them. He merely demonstrated thechemical nature of fire and combustion. Theexplanation of the actual " mechanism " ofthese chemical processes was to come at aconsiderably later date.Burning is Oxidation

We know nowadays that when a substanceburns, its atoms (or a portion of them)enter into chemical union with the, atoms ofoxygen in the surrounding air, forming aninvisible gas which at once escapes fromthe sphere of the burning. Burning, there-fore, is merely a species of oxidation. So,too, is animal breathing, the 'rusting of iron

The miner's lamp, an indispensable aid to coal -mining. It is based on the simple principle

illustrated in the diagrams given below.

and the tarnishing of many other metals.Clearly, however, something more than

mere con: act of the oxygen atoms and thecombustible material is usually necessary tostart the burning. We .may stand a candlein a jar of oxygen for ever and a day, but,under normal circumstances, the candle willnever take fire of itself. The truth' is that,normally, before the groups of atoms whichare susceptible of combustion changes canbe made to take part in a process of com-

bustion they have tohe, as it were, acti-vated." This activa-tion is usually broughtabout merely by rais-ing their tempera-tures. When a bodyundergoes a tempera-ture -rise the move-ment of.its constituentparticles or atomsincreases. VL hen thisatomic 'movementbecomes sufficientlyintense, the oxygenatoms and the atomsof .the combustiblesubstance attract oneanother. They enterinto a chemical union,this process usuallybeing carried out with

so great a degree of violence that the atomicand molecular movements become manifeStto us by their production of light and he:at.

Without going into elaborate detail overthis matter, we may now state one veryclearly observed fact. It is this : 'Before anycombustible material can undergo' the pro-cess of burning, it must first of all beheated up to a certain minimum tempera-ture, which temperature is now known as theignition point of that material. The ignitionpoint once reached, combustion or burningproceeds Continuously and automatically solong as the necessary supplies of oxygen areavailable.

Ignition Point and Flash PointGreat care should be taken to distinguish

the term -ignition point from the expressiOnflash -point," which latter is very much

used in industrial circles in connection withthe properties of liquid fuels and oils. The" flash point " of an oil is the temperature atwhich it begins .,.to give off an inflammablevapour, whereas' the ignition point is thetemperature to which that vapour must beheated (locally) for its combustion to beinitiated. Careful reflection will show thatthere is a vast difference between these twoterms. Flash points are usually relativelylow ; ignition points or ignition temperaturesare normally high, being well above the500 degrees centigrade mark.

A few materials, however, have abnormallylow ignition temperatures, notably that evil -smelling liquid* known as .!` carbon di-sulphide," the vapour of which requires tobe locally heated to only a temperature, ofaboin 95 degrees centigrade (below thetemperature of boiling water) for it to igniteand to burn continuously.

Once a substance has been raised intemperature to its ignitioh point, the heatof its ensuing combustion enables successiveamounts of the substance to attain the neces-sary ignition temperature, and thus thecombustion process becomes automatic.

The process of burning at once stopswhen we cool down the burning substancebelow its ignition temperature. A well-known laboratory experiment clearly demon-strates this fact. If a piece of wire gauzeis held about half an inch above a bunsenburner from which gas is issuing, and if alight is applied above the gauze, it will be

" Electrical flame "-a photograph of the flameof white-hot, glowing carbon vapour existingbetween the -carbon electrodes of a high -power

arc lamp.


A Poser from Muggins" You fancy yourself as a mathematician,"

said my friend Muggins to me the otherday. " Here is a little problem for you. Ihave just spent ten shillings on cigars,buying some at 3d. each, some at 7d., andsome at a shilling. How many did I buyof each kind ?

" I can't tell you," I replied, " unless_ yougive me some further information."

" Well," said Muggins, " here is anotherhint for you. The total number of cigars Ibought is equal to half the number of _yearsin your age. Now can you answer thequestion , "

" No," I told him. I still can't."How old am I ?

Brides and Their Brothers" We had a quadruple wedding at our

church 'yesterday," said Albert Hill. "Eachone of the brides was the sister of one ofthe grooms.

" My wife's brother married Susan, andher brotheronarried Miss Gill," he went on." Mary's brother married my sister.Constance is Mrs. dill now ; and Mrs. Dill'smaiden name was Quill."

" It all sounds very complicated," I said."Possibly," replied Albert. " But on the

strength of what I've told you, ,you oughtto know Clara's married name."

What is it ?

found that the gas will burn above thegauze but not below it. This effect is dueto the cooling influence, of the gauze on thegas, for the wire gauze conducts away heatso rapidly that the issuing gas below the'gauze is not able' to attain its ignitiontemperature. Only after the wire gauze hasbecome red hot does the gas Stream belowthe gauze take fire in consequence of itsthen being heated up to its ignition point. -

Again, if a cool piece of wire gauze isbrought down on to the flame of a bunsenburner, the gauze at once extinguishes theflame above it. Nevertheless, the gas passesthrough the gauze, as can be proved byigniting it above the gauze by means of amatch.The Miner's Lamp

This cooling power of a wire gauze inforcing down the temperature of a burninggas below its ignition point and therebyextinguishing the flame was brought into,'valued use by both Sir Humphrey Davy, thechemist, and by George Stephenson, theengineer, in the production of miners' lamps.In these lamps, the burning wick is sur-rounded with a wire gauze cage. Althoughany combustible gas, such as the " fire-damp " of the mines, can pass into this cageand can actually burn within the cage, theflame of its burning cannot pass outside thewire gauze and so ignite the gas in thesurrounding atmosphere. By this simplemeans, the " safety lamp " at once estab-lished its position of industrial importanceat the beginning of the last century.

The difference between burning and rust-ing is merely one of degree and not of kind.Burning and rusting, as we have previouslyseen, are both processes of oxidation. Burn-

_ ing is a rapid oxidation. Rusting is a slowoxidation. It is possible, however, to havewhat we might term a " rapid rusting," for

' if iron is heated to a white heat and plunged

into a jar of oxygen, the metal will actuallytake fire and burn with a dazzling whitelight, producing a compound of iron andoxygen-iron oxide. It is true that the blackiron oxide produced by the oxygen -burningof iron is not precisely the same as thered oxide produced by the slow rusting ofthe metal: Nevertheless, the two principlesare identical, the rusting sand the burningbeing merely processes of oxygen -combina-tion, or, " oxidation," as it is now calledin modern chemical parlance.

Flame and fire are due to rapid com,bustion. The rusting of iron and thetarnishing of many metals are caused byslow combustion. Certain oils, such asturpentine and linseed oil, very slowly absorboxygen from the air (particularly, under theinfluence of traces of materials known as" driers ") and become solid. Here againis a species of slow oxidation which we areeveryday acquainted with, since it is on thischaracteristic property of turpentine andother oils that the properties of the oldertypes of paints are based.

Spontaneous CombustionIn some circumstances, oxidation may

proceed slowly at first. But, given certainconditions, the heat of the oxidation may notbe dissipated adequ'ately. Consequently,the produced heat will tend to accumulate inthe combustible or oxidisable mass ofmaterial. As a result of this, the materialwill heat up still more. Its rate of oxidationwill increase. This increased oxidation willraise the temperature of the mass still higher,and having once started, the sequence ofeffects will be continued until' the com-bustible material will be raised in localtemperature to its ignition point. Once thistemperature has been reached, the materialwill at once break out into open fire or flame.It will be said to have " self -ignited."

Such is the explanation of the mysteriouscases of spontaneous combustion which weall have heard of from time to time. Thereis nothing inherently perplexing in .spon-taneous combustion; 'although cases of thisphenomenon usually occur under mysteriouscircumstances. Oxidation processes due tomould and mildew attack in hay andhayricks are quite capable of leading up toeventual spontaneous combustion. Such, too,are the well-known heating effects of manureheaps and of other chemically active massesof material. Reinember, always, therefore;that spontaneous combustion is merely amatter of a mass of material having had itstemperature raised locally above its ignitionpoint by one cause or another, and anyprofound mystery enshrouding such aconflagration will at once vanish.The' Significance of Breathing

Our bodies, as we have . noted, areactivated by a combustion process just asmuch as a steam or an internal-combustionengine is. When air is inhaled into thelungs, the oxygen of the air 'passes throughthe thin walls and tissues of the lungs intothe mass of blobd vessels situated therein,and it immediately forms a loosely -heldunion with the haemoglobin, or the colouring -matter of the blood. The resulting oxy-hwmoglobin is bright red in colour. It flowsto all parts of the body and its oxygen loadis utilised in oxidising or burning up the lacticacid and various other waste products whichare formed by the cells, tissues and muscles.Carbon dioxide gas and water are producedin this oxidisation process. The former isconveyed back to the lungs loosely combinedwith the haemoglobin: It is then given upand exchanged for fresh oxygen. Hence,we breathe in oxygen and breathe out carbondioxide, the product of the continual com-bustion or oxidation which is taking placein our bodies.

Probes and ProblemsSome -Mental Nuts for You to Crack

(Solutions are given on page 135.)

A Mathematical CertaintyHere is a little puzzle that may serve as a

tribute to our Russian- Allies. We are allconfident that the SOVIET FORCES spell-VICTORY. The problem, therefore, is tosubstitute figures for letters in the followingsum in addition. (Naturally, the same letteTalways represents the same number.)

SOVIETFORCES

VICTORY

League FootballIn our local football league Aytown,

Beetown, Ceetown and Deetown competed,finishing in that order. Each team playedeach of the others once, and . points wereawarded on the basis of 2 for a win and

for a draw. If points were equal, positionwas to be decided on goal average.

Curiously enough, each individual gameproduCed the same total number of goals,although. no team made the same scoreagainst any two opponents.

Aytown won all their games, with theexception of a draw against Beetown.Ceetown beat Deetown by 4 goals, the latterteam failing to score.

It is required to construct the entireleague table.

A Geography LessonHow many places are there in the

world," said Binks Minor, " all the samedistance apart ? "

" Millions," promptly replied Perkins.Tomkiiip scratched his head a little

doubtfully. " don't quite see what youmean," he said. " I suppose you could havedozens of places4each a mile away from thenext one."- " Yes," answered Binks, " but the first

needn't- be a mile away from the last. Imean, supposing London is the same dis-tance, from New York as it is from Moscow

" It isn't," put in Tomkins." All right, clever. I only said supposing.

Then if New York were the same distancefrom Moscow, that Would be three of them.I wonder, could you have more thanthree ? "

" No;' said Tomkins.Nonsense," said Perkins. " You could

have thousands of them."What is, in fact, the largest number of

places that can be found in the .world all atthe same distance from each other ? And,for the benefit of those who like a moredifficult problem, what would that distancebe ? (The diameter of the earth may betaken as roughly 7,920 miles.)

(To be continued.)


Vacuum -cleaner MaintenanceHow to Carry Out Simple Repairs.

THERE are few domestic appliancesthat are appreciated as much as -thevacuum cleaner. In these days the

purchase of a new cleaner is practicallyimpossible through the wartime restrictionof manufacture. Therefore it behoves thepossessor of one to spend a little time andpatience on it, if he or she desires to obtainthe maximum life and service.

Although the general principle of opera-tion is the same, most modern cleaners haveevolved into two types. One pattern hasan external dust -bag suspended from thehandle, whilst the other has the dust -bagenclosed in a cylindrical container.

Special attachments enable one to cleanupholstery, heavy curtains, etc. The external -bag machine, however, employs a rathermore powerful motor, which results' in astronger suction. It can also be run forlonger intervals without emptying the bag,due to its larger capacity.

An impellor, or motor -driven fan, consti-tutes the main feature in both, and isoperated at high speed for creating avacuum. The air -rushes through thematerial that is being cleaned to fill thevacuum, carrying with it dust and dirt

. particles, etc. Eventually it reaches the dust -bag, where the air disperses through the finemesh, leaving the dust, etc., behind.

Some external -bag machines have as anadditional feature an agitator, which inprinciple is a revolving brush driven by themotor through a simple transmission system,mostly by an endless rubber belt.

Inspecting the MotorFrom time to time it will be necessary to

inspect the motor. In the cylindrical models,remove the air exit cover. In the external -bag type it will only be necessary to removethe top cover to expose the motor.

The motor runs on ball -bearings, whichare usually packed during manufacture witha special grease, which runs for extremelylong periods without attention, thus obviat-ing frequent lubrication of a ratherinaccessible point.

The commutator should next be carefullyexamined for any accumulation of carbondust from the brushes in its segment gaps.If such is the case, sharpen a match to apoint arid carefully remove the dust frombetween the gaps.

After long use it is to be expected that thecommutator will be discoloured and dirty,and in this state is electrically inefficient. Toremedy this defect, hold a piece of veryfine glasspaper against the commutator withone hand and turn the armature with theother, until it is perfectly clean.

Now replace the glasspaper with a pieceof clean rag, moistened with petrol ormethylated spirit. Be careful not to over -wet the rag with the spirit, as it is a strongsolvent of shellac, which is often used forinsulating purposes in the armature.Revolve the armature, changing frequentlyto" clean portions of the rag, until it comesaway unsoiled.

To inspect the brushes, remove first theretaining plug positioned at the extreme endof the brush post or guide. A small coilspring will now be seen. Gently pullingupon this will remove the brush from itshousing. (Fig. x.)

It is very rare for the brushes to requireattention. Points that should be observed

By E. S. BROWN

are that they are free from cracks, in whichcase, of course, renewals will be necessary.

Switch TroubleWith some cleaners the switch is a con-

tinual source of trouble. Undoubtedly thewisest procedure to adopt is to leavethe switch permanently on, and operate thecleaner by removing or replacing theconnecting plug.

Sometimes, however, the trouble is simplycaused through the breaking of the small

Fig. x.-Brush assembly, consisting of bush,spring and plug.

Fig. 2.-Type of unitswitch fitted to somevacuum -cleaners whichcannot be repaired.A replacement is

necessary.

coil spring which actuates the snapmechanism. If a similar spring can beobtained, it can be quite easily fixed. Oneend of the spring should be fixed on to thelocating pin, then compressed so that uponrelease the other end locates itself on thetumbler pin. (Fig. 2.)- As the cleaner's dust-removing properties

depend upon good suction, particular atten-tion should be occasionally given to see thAtthe various connections between themachine, hose and accessories are airtight.If a leak is suspeCted, a smear of soap beforeassembly will in most cases effect a cure.

2 3Fig. 3.-Various stages in lead repair. 1. Leadcut, and wires divided in various lengths.2. Wires ioined and insulated. 3. Repair

completed.

See also that the end cover fitting on to thecleaner beds down firmly and evenly onto the rubber ring, and that the holding -down clips work satisfactory.

Defective LeadsWith a cleaner that has seen much service

a somewhat obscure defect sometimes occurs.This asserts itself by the cleaner mysteriouslycutting off and on during use. The troublecan usually be traced to the lead carryingthe current to the machine having aninternal fracture.

With current switched on, carefully bendthe lead in alternate directions along itsentire length. At one point the movementsof the lead will connect and disconnect thecurrent to the cleaner.

It is, of course, far more satisfactory toreplace a defective lead with a now one,but in these days such a procedure cannotalways be adopted. Therefore, if throughnecessity or otherwise, it is decided to retainthe old lead, a satisfactory repair can beeasily carried out.

Incise the lead in two at the point offracture and, for about 3M. along eachlength, remove the outer covering to exposethe insulated wire beneath. The wiresshould next be Cut into two varying lengths.(See Fig. 3.) Remove sufficient insulation toallow for joining, and preferably solder therespective ends together. Next wind insulat-ing tape very firmly around erh join andfinish by applying further insulating tapearound the entire repair, taking care toprovide a good overlap on the severed endsof the lead.

Germs breed prolifically in dust and dirt.A worth -while tip is to slightly moisten -a small sponge with a disinfectant, one ofthe pine oil varieties are very pleasant, andplace inside the dust -bag.

StoringTake particular care where the -cleaner

is stored. At all costs avoid storing in adamp atmosphere.

The ideal storing conditions should bea place that is well ventilated, dry and cool.The cylindrical model should be stored onend with the motor end undermost.

Dust -bag RepairsWith normal usage the dust -bag should

last many years. Should, however, a'slighttear occur as the result of an accident,immediate steps should be taken to effecta repair.

The tear should be carefully drawntogether with carpet thread; then, aftercleaning the surrounding parts, apply somerubber solution liberally on both sides. Twopatches of thin calico will now be required.They should be cut to allow at least /in.overlap all around the tear. Rubber solutionshould now be applied to the patches, thisbeing well rubbed into the material with theforefinger.

Allow a reasonable time for the solutionto thoroughly dry on the parts to berepaired, then apply a second application.When the prepared surfaces are again dry,affix the patches to the tear, one inside, theother out. Press outwards from the middleof the patches, and then firmly fix in place ;apply a fairly hot domestic iron to them,maintaining as heavy pressure as possible.After about a minute the repair will becompleted.


A Perpetual CalendarAn Easily -made Calendar Which Quickly Gives theDays of the Month for Any Year from 1925 to 1980

BY following the simple instructionshere given anyone can make anextremely useful , calendar, 'which,

by the simple process of setting the monthagainst the year, will show the correctcalendar for that month ; it additionallyrives the back years as far as 1925, which are

Class Front

BifurcatedCalendar Face

PiercedDead Centre

cam_ Washer fOr

Spacer in Which Disc Rotates

Slightly LargerSlightly Thicker than than Disc DieDisc Thickness

Fig. 4.-Hozo the parts are cssembleck

//

THIRTY DAYS HAIMSEPTEMBER.

APRIL. JUNE. ANDNOVEMBER:

ALL THE REST HAVETHIRTY-ONE.

EXCEPTINGFEBRUARY ALONE:

WHICH HATH BUTTWENPfBCRI DRS MAR.

AND TWENTY-NINEIN EACH LEAP -YEAR

sometimes most useful, and goesahead as far as 1980, which islong enough for most of us tocare to think about. The com-pleted. calendar is shown in Fig. i.

The chief parts for making thecalendar consist of the " basiccircle," shown in Fig. 2, and thecalendar front, Fig. 3. To enablereaders to easily make up thisuseful unit we have had the twochief parts printed on tinted cardto a slightly larger scale thanthe illustrations Figs. 2 and 3.By this means it is a simplematter to cut out the parts andassemble them as describedbelow.

Having cut out the basiccircle" save the outside portion,which should be stuck down toanother piece of cardboard andthen trimmed down to the circlea little larger than the " basiccircle " still showing on the card.Now cut out the shaded slits in Fig.Bevel off the :;in. strip round the openingsthus cut out, starting with a razor blade,or sharp penknife, and finishing withglass-paper. Whiten over the bevelled edgeswith ivory -white colour, and cut out thethumb hole shown on the right edge of Fig. 2,and a similar one on a piece of cardboardwhich will be the backing board. Thisshould measure 5;',in. ; 41in.

Readers may obtain the two partS of thecalendar in this larger size, printed in twocolours on stiff board for is. 6d., post paid;from the publishers,George Newnes, Ltd.,Tower House, Southampton St.,Strand,W.C.2

To assemble, drive . a flat -headed nailthrough the centre hole of the calendar -portion (Fig. 2) and through the centre ofthe circular piece (Fig. 3). Place the partsin ,pbsition and drive the nail on through thecentre hole of the backing board (Fig. 4).

Smear glue on the meeting surfaces,press into position, and make allsecure with some small fretwork pinsalong the edges. Glue on at the

2

Fig. 1.-The finished calendar and stand.

PassepartoutBinding

Fixed to Rackct Calentlir

Fig. 2 (left).-The calendar front.Fig. 3 (above).-The "basic cisrcle.!

Tape

GummedLinen The.

Steno,

Fig. 5 .-Method of fixing thesupporting leg.

back a suitably shaped pieceof cardboard for a leg, heldfrom going too far back witha piece of tape of a suitablelength (Fig. 5). Secure the

_ends of the tape with glue andcover than over with stripsof passe-partout binding tapeto make doubly sure.

Having cut a piece of glassto the reckuired size, cut outthe semi -circular thumb -holewith a glass cutter and finishthe edge smooth with a smallcarborundum wheel. Finally,bind the complete assemblywith passe-partout rape, asshown in Fig. r.

January, 194 4 NEWNES PRACTICAL MECHANICS 131

Inventions of InterestFloating Runway

THE future of flying after the war will nodoubt be characterised by remarkable

developments. We shall not be able literallyto build castles in the air as stations foraeroplanes, but one does not need to be aprophet to foretell that runways which float '

on the sea will be a feature of aerial navigation.In connection with this prospect it is

interesting to note that, the subject of acurrent application to the British PatentOffice is a structure of the nature of a raftwhich has been designed as a floating runwayfor starting and landing aeroplanes.

The device includes a hinged extendingplatform supported by hinged extendingarms floated by a series of rectangular floatsbetween the arms under the platform. Thereare also two half -cylinder floats at the endsof the platform.

DistTess SignalTHE shipwrecked 'mariner on a raft has

been known to improvise a signal ofdistress in the shape of his fluttering shirt.This crude method has now been far surpassedby an improved -visual signal whereby a lighton a lifeboat or other craft may be displayedto solicit aid " for those in peril on the sea."

The invention comprises a rotatable lamphaving an aperture for emitting a beam oflight. This aperture has a shutter whichcan be moved between screening and non -screening positions. There is an actuatorfor the shutter mounted on the lamp

Gear is provided operable by motive powersupplied by a spring motor which is woundby a key.

Buoyant RopeTHERE has been applied for in this country

a patent for a rope which will floaton sea or fresh water for a considerable time.

The inventor of this buoyant rope, pointsout that when cotton and other fibres aremade up into rope by stranding, plaitingor braiding the resulting rope may have anapparent specific gravity less than one. Butif left in contact with water it will absorbthe water more or less rapidly and theinterstices will be filled with the liquid. As aconsequence the apparent specific gravitywill be raised to a value greater than one.

The new device consists of a flexible ropeformed of fibres rendered water-repellent bymeans of a wax or fat or both applied as anemulsion. It has an apparent specific gravityof less than one and it is stated to be capable offloating on water for more than one day.

Handy HandleAT the present time there is a most

annoying scarcity of teacups. As aresult, even chipped china is at a premiuniand crocks are not necessarily consigned tothe dustbin.

We have not yet attained to the philosophyof Diogenes, who, when he saw a boy drinkingout of his hand, threw away his cup.Therefore it behoves us to adopt any methodwhich will enable us with the minimum ofinconvenience to imbibe the cups thatcheer but not inebriate.".

It has hitherto been 'proposed to furnisha handle which can be attached to cups andlike receptacles. In the case of one suchproposal the handle has been secured inposition by means of a hand which enclosesand is drawn tightly round the receptacle.According to another idea, the handle at one

By 'Dynamo"end is in the form of a resilient hook adaptedto fit over the rim of the vessel and to bearagainst the inner and outer face while theother end bears against the outer face.

A recent invention has for its aim the fixingof a handle to cups made without the usualhandle and known as utility or austerity cups,

The information on this page is speciallysupplied to " Practical Mechanics " byMessrs. Hughes & Young, Patent Agents, o7, 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."

and also to cups with handles broken off,tumblers, etc.

According to this invention a handle isprovided with a shoulder or abutment toengage with the rim of the vessel and therebyprevents the handle slipping doWn. Andthere is a band which encircles ,the vesseland secures the handle.

The two ends of the band may be connectedto a pin in a slot in the handle, the tightening

Hitherto the attachment of gas curtains tocivil defence helmets, even by an experiencedperson, takes a considerable time, and thishappens at a juncture when speed is of verygreat importance. Consequently, it appearsthat, contrary to regulations, it is oftenthe practice for civil defence personnel tohave their gas curtains permanently attachedto their helmets. This practice, however, hasthe disadvantage that the edge of the curtainbecomes worn through, rendering the curtainuseless for protection.

There has recently been submitted to theBritish Patent Office a simple device by meansof which an article may be practicallyinstantaneously attached to or detachedfrom a helmet even by an inexperiencedperson.

An additional object of the inventor hasbeen to furnish, in combination with the abovedevice, an improved form of gas curtainwhich may be folded compactly and carriedin the gas maslc haversack or other receptacle.At the same time when adjusted over thehelmet, it leaves no part of the face exposed

to liquid gas.

This Heath Robinson contraption provide's the hot water(under pressure) for a welcome shower for Allied airmen

on an Italian airfield.of the band being effected by adjustment ofthe pin in the slot.

The handle may carry a screw which, whenrotated, will bear on the vessel and therebyforce the foot of the handle therefrom andtighten the band.

To enable the vessel to be thoroughlycleaned the handle is removable.

Helmet AttachmentIT is frequently necessary to attach various

articles, such as camouflage devices andnets, to military helmets and gas curtains tothe helmets of civil defence workers.

Anti -gas Balaclava'THE quick helmet attachment

in question comprises aportion adapted to fit over thecentral part of the crown- of thehelmet. There is a resilient striphaving at its extremities clipsintended to fit over thebrim of the helmet. And inarrangement is provided forsecuring the device to theparticular article which is to beattached to the helmet.

As regards the improved gascurtain, this comprises whatmay be described as a large -size Balaclava helmet formed toextend over the shoulders ofthe wearer.

The curtain is made of gas -proof material such as oilskin.Open in the front, it hasfastening means such as snapor sliding quick -fasteners, sothat any desired degree of closingmay be obtained. A draw cordis supplied for closing the curtaintightly about the gas mask.

To attach the curtain all thatis necessary is to place the opencurtain over the helmet, so thatthe centre piece recess formedby an annular pad engages thehelmet bolt head. Then the twoeyes of attachment means arecaught and they are drawndownwards until the clips arebeyond the helmet brim. The

clips are then drawn up into engagementWith the brim. The front of the curtaincan be closed to suit the' convenience ofthe wearer.

NEWNES ENGINEER'SVEST-POCKET ROOKBy F. J. CAMM 10/6 or by post 11/.

Obtainable from all booksellers, or by post fromGeorge Newnes, Ltd. (Book Dept.), Tower House,

Southampton Street, London, W.C.2.


THE WORLD OF MODELS

Scene on the Sankey model railway-a small harbouron an inland canal with boat alongside the quay,a picturesque windmill and a mixed traffic train by

the quay.

IT hardly seems " cricket to write aboutmodel railways when there are so manykeen to have them, but owing to war

conditions they can obtain no equipmentexcept second-hand through a private source,for the Government at present forbids thesale by dealers of finished models containingmore than to per cent. metal, unless thesehave some historic value.

But those who have model railways stillfind them a great relaxation from their wareffort, besides the " younger generation "who have grown from little boys " to modelenthusiasts during the war years. These" lucky people " can continue to improvetheir grouts by individual effort with anymaterial available, and in looking throughmy post -bag I have come across a fewexamples which show that work is stillproceeding.

Some Realistic Model RailwayLayouts

By "MOTILUS"before he departs for his own work, whichis also helping the war effort.

Photographing Model Railway StationsA friend has asked me about photograph-

ing views of model railway stations. This is

Another scene on the Sankey model railway-an Apline type scene withits distant view of pine trees, a chalet and a small rustic waysidc station.

a chalet, and a small rustic wayside stationwith electric locomotive drawing two Mitropadining cars, evidently bringing imaginarypassehgers for an imaginary holid'-atleast until peace breaks out !

And Mr. Sankey deserves his relaxation.His wife works on munitions, which meanshim rising at six a.m. to see to breakfast

An uriZarianiiia-shot of the inside of 5-iiwdelrailway- station, taken on Mr. Gilbert Thomas's gauge

" 0 " railway.Sankey Model Railway

Firstly, there is our friend, Mr. H. M.Sankey, whose work has been featured inprevious issues, especially in connectionwith the modelling material " Pyruma."

Here are two photographs of sections ofhis son's railway, which is continually beingdeveloped. . The first shows a small har-bour on an inland canal with boat alongsidethe quay, a picturesque windmill in theforeground and a mixed train alongside thequay.

The second illustration is of an Alpinecharacter with its distant view of pine trees,

not an easy matter unless you have a shortfocus lens as used in conjunction with 35 mm.cameras, which gives great depth of focus,and enables you to get close to the job. .

Here is a photograph taken with such acamera of Mr. Gilbert Thomas's gauge" 0 " railway when it was in the Londonarea. It shows the inside of a terminusstation with a G.W.R. King George V loco-motive alongside the platform. Did younotice the famous brass bell on the bufferbeam, which is a souvenir of the' realengine's visit to the New World ? It wassent across the Atlantic in 1927, and repre-sented Great Britain at the Fair of the IronHorse in Baltimore.

A Model Terminus StationThis photograph-from another angie-

of a terminus station is taken by R. Wisbey,of Burton -on -Trent,' and is a view of hisNottingham railway which took about twoand a half years of his leisure time to build.

" All the tools I had when I built mylayout," he writes, " were a pair of pliers, asmall screwdriver, a 2 -inch vice, two smallfiles, a hammer, and soldering iron."

The buildings were made of plywood,compressed cardboard, building papers, andCellophane material. The complete lengthof track is approximately 65 yards (in thisthere are four cross-overs, three facing and

Terminus station on the model railway of Mr. R. Wisbey, of Burton -on -Trent.

9

January, 1944.

The " O " gauge model railway of Mr. CecilA. Moore, of Leicester.

one trailing, one set of points' facing andthree trailing),- and it was constructed byMr. Wisbey from Bassett-Lowke steel andbrass rails with cast slide -on chairs laid onsleepers and fastened down on a plywoodbase.

The railWay was driven by electricitysupplied through a converter, and this wouldwork three trains with ease. In wartimedays, howeVer, Mr. Wisbey had to fall backon batteries, and have them recharged atintervals. In the track circuit he has madequite a few switches ,to isolate sections to

' ..11..4L

A corner of the model railway, giving a side viewlocomotive.

NEWNES PRACTICAL MECHANICS 133

work in conjunction with the signals. Thelocomotives he possesses are the L.M.S.R.Princess Elizabeth with new type tender,2-6---o L.N.E.R. Mogul, two L.M.S.R.4-4-o Compounds, and an o -6-o tendergoods L.N.E.R. locomotive, also eightL.M.S.R. bogie coaches (including one mailvan), and Iwo L.N.E.R. bogie coaches.

As to goods rolling stock, he has tenready-made vehicles, and made the othereighteen four -wheeled goods wagons frombought parts.

His main through station is 6ft. 6in. long,and there are four platforms complete withall details. There are up and down mainthrough lines, and a slow through line onthe inside oval layout. There is also atrailing crossover in the station.

Items which add to the interest of hislayout, and which any handyman can make

of the King :Tomes I express

for his railway, are a petrol storage depot,a tunnel, engine shed, and the carefuldetail he has achieved with the stations.

A Gauge " 0" LayoutMr. Cecil A. Moore, of Leicester, has

sent me pictures of 'his railway, which, heinforms me, he prepared for a 'eine film hewas hoping 'to make, but " owing to thewar "-how often have we heard that phrase-and the difficulty in obtaining film stock,the idea had to be abandoned.

The layout is gauge " 0," and he tellsme some of the components are not whatthey seem. For instance, the small o -6-otank locomotive is a mere dummy, mademostly from wood, and is used for effectrather than work. All the rolling stock ismade with wood tops, and axle boxes andB -L wheels, buffers, and couplings, mountedon wooden chassis. The wood tops have

in card strips glued on to the faces to

of a

r 'APO

another view of the ,attge " model railway.

give a tongued and grooved effect. All thewindows are glazed with celastoid, the in-teriors being of Cellophane. The painting,lining, and lettering are by hand.

Tlie locomotive power is clockwork, andthe engine, King James I, is made fromblueprints, and from various photos ofG.W.R King class locos.

The track is B -L scale model permanentway in 2ft. lengths, mounted ori

boards with end battens, which are lippedalternatively to .fit exactly into one anotherand clipped together on the sides with snapclasps. Signal boxes, factory, and variousother things are fixed direct on to the I -inchboards, and brick papers were used exten-sively throughout. The water tank is madefrom a paste aluminium container, painted.The signals have been glazed with greenand red Cellophane.

The whole effect, as seen in the photo-graphs, is very realistic, and let us hope itwill not be long before Mr. Moore is ableto carry out his project of a model railwayfilm.

Rationed ElectricityTHIS is the age of rationing. A method

of controlling the consumption ofelectric current is the subject of an applica-tion to the British Patent Office.

The inventor points out that there arefrequent occasions when an electricity supplyundertaking wishes to limit its maximumoutput. For example, it may be desired toreduce the range between the peak loadsand the mean loads in a daily cycle, or toeffect a scheme of current rationing inwartime. Also it may be required to dealwith sudden increases of load on particularcircuits on the occasion of a fog or someother exceptional occurrence.

The object of the invention in questionis to limit each consumer to a predetermined

vari.ble maximum load continuously or atregular int, rvals, or at any intervals deter-mined by circumstances at the time. And thisis done in such a way as to allow of theconsumer adjusting his circuits to thatmaximum, except in the special cases whena complete cessation of supply is necessary.

The proposed method of controlling themaximum consumption of current fed to acircuit from supply mains consists inproviding in that circuit a load -responsivecircuit -breaker whose maximum capacitymay be caused by the normally suppliedcurrent to pass through successive identicalperiods of variation, and in varying thecapacity by means of such current.

134

Masters of Mechanics -92

NEWNES PRACTICAL MECHANICS January, 1944

General ShrapnelThe Inventor of the Shrapnel Shell

IT is said that Sir Hiram Maxim, pioneerof the machine gun, used, at times,rather pensively to claim that his

invention had been responsible for more menbeing deprived of a natural death than anyother single device, invention or creationin the world's history.

Probably Maxim was right in his asser-tion. Nevertheless, Lieutenant -GeneralHenry Shrapnel, who lived and experimentedin the stormy days of the great Napoleon'srise to power, and the Duke of Welling-ton's Continental exploits, was a closerunner-up of Maxim's in respect of theinvention of a mechanical means of bringingabout the violent and abrupt cessation ofhuman life in wartime.

The name " Shrapnel " is far better knownthan that of the early nineteenth -centurymilitary inventor who then owned it.Posterity has forgotten the man, but it stillclings tenaciously to the seemingly indis-pensable principle of his death -dealinginvention. jndeed, had there been no suchthings as War Office personal records, wemoderns would have known very little indetail about the career of the man Shrapnel,for the greater part of his inventive workwas necessarily secret and, as an individual,he was seldom, if ever, within the publicgaze.

Wiltshire BornThere is quite a common yet totally

erroneous notion that Shrapnel, the origin-ator of the, famous projectile bearing hisname, was a foreigner, and even that he wasa German. As a matter of fact, HenryShrapnel was a Wiltshireman, having beenborn at Bradford -on -Avon, in that county,on June 3rd, 1761. Few particulars con-cerning Henry Shrapnel's earliest years areavailable. We only become away of hiscareer in detail when, on July 9th, 1779,.at the age of 18, he was gazetted a 2ndlieutenant in the Royal Artillery, in whichcapacity he was drafted off to Newfound-land in the year following. In 1781 he waspromoted to the rank of 1st lieutenant, andhe was returned to England in 1784.

He studied ordnance in all its aspects,and after he was returned to England by hissuperiors he commenced in a small way towork out one or two of his -own ideas in theway of ordnance projectiles. These experi-ments were conducted by him mainly in hisleisure hours, and entirely at his ownexpense. Exactly how Shrapnel commencedhis experiments is not known. Nevertheless,they must have been important and signifi-cant experiments, for they culminated inthe producliOn of the shrapnel shell.Gunpowder Bombs

The type of military projectile named afterHenry Shrapnel consists, in principle, of ametal container or shell having within it alarge number of bullets which are releasedby the bursting of the shell and which thentravel forwards with a high velocity. HenryShrapnel was, perhaps, by no means thefirst originator of- the basic idea whichmaterialised in the shell named after him.There are records of canisters of gunpowder,so-called bombs, which burst under theinfluence of a crude type of fuse and whichscattered around them various odds and endsof metal fragments and the like.

The first shell devised by Shrapnel was acurious form of hollow sphere which was

filled with lead lumps. The thin -walledsphere Was burst by a gunpowder charge,which was set off by means of a fuse ignitedby the firing of the ,gun.

Shrapnel experimented with these shellsby firing them from both light and heavycannons, but, as could be expected, they wereextremely unreliable in action, their greatestdrawback being the extremely crude type ofgunpowder fuse which was provided forthem.

General Henry Shrapnel, inventor of thefamous artillery shell principle.

The military authorities failed to shareeven a portion of the enthusiasm of theenergetic Shrapnel. In order, perhaps, todiscourage him or to remove him, as theythought, to, a greater sphere of usefulness,they shipped him off to Gibraltar in 1787,and, afterwards, to a succession of militaryposts in several of the West Indies posses-sions.

Eventually, however, Shrapnel returned toEngland, and in the same year (1793), he wasraised to the rank of " captain -lieutenant."His next military experience comprisedservice in the army of the Duke of York inFlanders. He was wounded at the siegeof Dunkirk, which took place in the Septem-ber of 1793, but even in this crisis it isrecorded that he had the originality and the

An old-time " Carronade," used for navalwarfare in the time of Napoleon.

clearness of mind to lock the wheels of hisgun -carriages so that they could be skiddedrapidly over the hard, dry sands, and, also, tolight fires, away from the British positionsfor the purpose of attracting the fire of theenemy, tactics which were entirely novelat that time.

In 1795, Henry Shrapnel was promoted tothe rank or captain. In 1802 he becamea brevet -major ; then a major in 1803, anda lieutenant -colonel in 1804.

Assistant -Inspector of ArtilleryThese military promotions seem to have

had little influence upon Shrapnel's charac-ter, for he delved more and more deeply intohis routine of experiments and trials. Fromspare -time ones, they became, in part," official " ones. So much so that, in 1804,Shrapnel was firmly established at the RoyalArsenal, Woolwich, as Assistant -Inspector ofArtillery, in which post he seized everyopportunity to develop the novel type ofshell which he had previously invented.

The shrapnel shell appears to have beenfirst used by the British in 1804, duringthe attack on Surinam, a colony of Guiana,which was originally settled by the Dutch.At first the new, shell was not altogethersuccessful. Although its principle was right,its design was wrong, and, mainly throughthe defects of its fuse, the shell was anythingbut reliable. Furthermore, the militaryauthorities, ever conservative, like their navalbrethren in those days, did not show anygreat liking for the novel projectile. It wasorgy after the Duke of Wellington had com-mended the shell in 1808 that Shrapnel'sprospects began definitely to brighten. TheDuke gave it as his opinion that the detailsof the shell should not be made public, andthat as the inventor, in consequence, wouldthereby be deprived of a considerable amountof fame and commercial success, he shouldbe properly rewarded " for his ingenuity andthe science which he has proved he possessesby the great perfection to - which he hasbrought this invention."

Thc first Shrapnel shells were made at thefamous iron foundry at Carron, near Falkirk,Scotland. At that time they were named" spherical case shot." This name remainedwith them for many years, for it was onlyin 1852 that the British Army authoritiesadopted the title of " shrapnel " to dis-tinguish this type of military projectile asa mark of honour and appreciation of thethen nine -years -dead inventor.

During the early years of the nineteenthcentury the Carron Company had a widereputation for the production of various typesof cast ordnance, including, among others,the famous " carronades," iron cannonswhich gained great fame on the Britishwarships. The workers at the Carronfoundry had acquired the technique ofproducing exactly the right variety of ironwhich was required for cannon production.That was why, perhaps, the first contractfor the manufacture of Henry Shrapnel's newshells was given to the Carron Companyinstead of to one or other of the RoyalArsenals, and particularly to WoolwichArsenal, in which many of the earliershrapnel experiments had been conducted.

Firing TestsIn the fields around the Carron foundry

the early practical firing tests of the shrapnel

January, 1944

shell were carried out under the supervisionof Shrapnel himself. Quickly Carron becamealmost as fitnous for its production of thenew shells as it had done for its manufactureof " carronades " and other pieces ofordnance.

The early shrapnel shells made at Carronranged in size from 3 -pounders for thelightest guns up to 68 -pounders. Apparentlythey were supplied at prices varying from6d. to 5s. each.

It was during the exploits of Wellingtonin the Peninsular War that the " sphericalcase shot," or, in other words, the earlyshrapnel shell, established its military posi-tion. Wellington himself, as we have alreadyken, went to the trouble of personallyrecommending the inventor for a reward.

An early light cannon which fired some of the first shrapnel shells.

All the British generals-and the admirals,too - began, one by one, to shareWellington's enthusiasm. It was GeneralSir William Robe, commander of artillery hethe Peninsular' War in Spain and Portugalduring the years , 1808-14, who wrote

NEWNES PRACTICAL MECHANICS .135

personally to Henry Shrapnel : " It [theshell] is admirable to the whole Army, andits effects dreadful "-rather an involved sortof a testimonial, but, nevertheless, sure inits meaning.

Admirals, with their man -o' -war " carron-ades," Aere similarly infected withenthusiasm for the shell. One of them, SirSydney Smith, actually wrote to Shrapneland implored him to expedite the dispatchof the new shells, even if he supplied themat his (the Admiral's) own private expense.

Shrapnel's RewardIn 1813 the rank of colonel in the Royal

Artillery was bestowed on Henry Shrapnel.And in September of that year he formallyaddressed the Board of Ordnance on the

subject of t hereward whichWellington h a dpreviously men-tioned. He pointedout to the Boardthat he hadpatiently and pains-takingly experi-mented, partly athis own personal -expense and in hisown leisure time,and that he hadexpended his ownprivate funds inpursuance of histrials and experi-ments to the tuneof several thousandpounds-.

To which appealthe members of theBoard of Ordnancelistenedcourteously.

Eventually they promulgated" their officialreply. It was to the effect that the Boardhad no funds at its disposal for the rewardof merit!

Less than a year afterwards, however, theTreasury granted Shrapnel a pension of

£1,200 per annum in addition to anyregimental or official pay which he might alsoreceive. That was Henry Shrapnel'sfmancial reward for his services to theBritish Army. Had he commercialised hisinvention he might have made millions.

Shrapnel's next Army promotion tookplace in the year 1819. It was to the rankof major -general, and it was with this rankthat he retired from the Army in 1825.

A couple of years later he received, inretirement, the title of Colonel -Commandantof the Royal Artillery, whilst ten years later,in 1837, the year of Queen Victoria's acces-sion, he was given his last military promotion-to the rank of lieutenant -general.

General Shrapnel retired permanently tohis residence, Peartree House, Southampton,and it was here that he died on March 13th,1843.

" Duplex Disappearing Mounting "The " spherical case shot " shell was by

no means the only creative product ofShrapnel's busy military career. During hiswork at Woolwich he improved the detailconstruction of several types of mortars andhowitzers. He invented a number of novelfuses, and he devised what was referred toas a " duplex disappearing mounting," whichlatter comprised a special . type of gun -mounting which so functioned that the recoilof one gun lowered the latter under coverand at the same time elevated the other gunto the correct firing position, a species ofalternating motion thereby being obtained.

Shrapnel further invented a brass tangentslide, and he improved the details of severalvarieties of rifles and small arms. He issaid, also, to. have spent a considerableamount of time and energy in compiling setsof artillery range -tables which enabledgunners to compute their ranges with a thenunheard-of rapidity and accuracy.

All such inventions have long ago dis-appeared into the vast limbo of obsoletecreations. The name of Henry Shrapnelnowadays lives on in popular memory solelythrough the :survival of his shell.

Solutions to Probes and Problems(See page 128)

A Poser from MugginsI am 36:It may be assumed that, since I "fancy

myself as a mathematician," I shall not makea mistake in a simple calculation. -Since,therefore, I was unable to answer Muggins'squestion, at least two answers to the problemmust be mathematically possible.

The question about the cigars allows ofmany solutions, but in only two cases willthe total number be the same, i.e., 9 at 3d.,3 at 7d., 6 at IS;, total 18; 4 at 3d., 12 at7d., 2 at is., total 18.

In either case my age must be 36.

Brides and their BrothersClara's married name is Hill. The

complete list is as follows:' Groom Bride

Dill Susan QuillGill Constance HillHill Clara DillQuill Mary Gill

A Mathematical Certainty491063592864

1083927

ABCD

League FootballGoals

A B C D WD,L FA Pts.X 2-2 4-0 3-I 2 I o 9 3 52-2 X 3-I 1-3 I I I 6 6 3

0-4 1-3 x 4-0 1 o 2 5 7 21-3 3-1 0-4 X I 0 2 4 8 2

A Geography LessonThere can be no more than four places

in the world all at the same distance fromeach other although there can, of course,be an unlimited number of sets of four.They are situated at the four points of aregular tetrahedron enclosed within a sphere.

The best way to visualise it is by imagin-ing inside the earth a pyramid on atriangular base, with the three points of thebase and the apex all just touching the surfaceof the earth.

The distance between the points ' will beapproximately 7,568 miles.

The "Gigant" Transport 'PlaneTHE Militaerische Correspondenz aus

Deutschland publishes an article onwhat is at the moment the largest aircraft inthe world, the German transport 'plane" Gigant."

German transport 'planes have repeatedlyplayed an important part in the fighting in theMediterranean, and in particular in themilitary operations which occurred in thecourse of the evacuation of Sardinia andCorsica. In these a new large transport 'planeof the evidence,Luftwaffe came into namely,the motorised transport 'plane e. 323,

Gigant," developed by Prof. Messerschmitt.An idea of the size of this aeroplane is givenby the following figures : The :span of thewings is 55m., the area of the wings is 3ooqm.and the cargo space too cubic ft. The cargo

space is so big that all bulky loads which arailway wagon can take can be stowed away.For example, the high load capacity of the" Gigant." makes it possible for 2i -ton lorriesor medium-sized tanks or guns, such as the8.8 cm. A.A. cannon, to be carried. Onnumerous occasions the "Gigant " hascarried no fewer than 13o fully equippedsoldiers, as well as 52 barrels each contaiLing250 litres of fuel; on ambulance work,it can transport bo wounded men in bunks.

The " Gigant " is constructed of woodand steel, a braced shoulder -wing monoplane(abgestrebter Schulterdecker). Six auxiliaryengines enable 'it to fly under its own power.The undercarriage consists of ten wheels inall and can surmount obstacles on theground like a caterpillar track.


Making a Success d Your Photography

A Real Winter's DayH.P. 3 filter. Exp. F8 so with 3 times filter. Developed with Azol.

Taken about II a.m. in January, 1943.

WHEN we thinz of winter our mindsusually turn to thoughts of snowscenes ; generally these are only

obtainable in January or February. I oncehad the pleasure of seeing a large portionof Ben Nevis covered with snow in July,but, unfortunately for me, 'I had beenpersuaded to leave my camera at home andto travel light, so as to reach the top ofthis wonderful " sight -yielding " mountain.I have never quite forgiven the friend whogave me this advice, and now, whenever Igo to a new spot of country, whether itbe mountains or lakes, my camera is aconstant companion.' Therefore, when youare off for a ramble in January, 'or at anyother tithe, have the camera charged. Snowscenes are often made in a night, and toget the real beauty of such it is necessary-to get out as soon as you can and whilethe light is good ; certainly before the snowhas had time to lose its brilliance.

" Pictorial PicturesIt is " novelty," I think, which induces

amateur photographers to use their camerason such occasions, for I am con-vinced that it is possible to waste more filmson snow effects than on any other subject ;by .this I mean that it is seldom one comesacross a really good " pictorial " result ofa snow scene in England.

What are the most essential featuresrequired to make such scenes beautiful ? Iwould put first and foremost sunshine andshadow, fbr without these you can onlyexpect to get hard contrasts and, in conse-quence, an absence of the delicate half tonesor tone gradations whiclf are of paramountimportance, in fact, necessary, when making" pictorial " pictures.

Sun effects on snow are obtainable, but,as already said, it is advisable to get outearly before the sun has_ had the chance ofhaving too much effect on the snow andchanging its surface.

The mention of surface brings me to my

Snow Scenes

Winter PhotographyBy JOHN J. CURTIS, A.R.P.S,

second essentialf eat ure -texture.Newly fallen snowwill give you this,especially while thefrost continues ; itssurface is bright,almost alive withsparkles, and t h esnow generally is'soft ; it has not hadtime to settle downin a solid mass, andthe sun hag notbeen able to breakup the delicate par-ticles or, as it were,the tissue of theflakes.

If, then, you Sinbe sure of securingsunshine and shadowtogether with tex-ture, by all meanstake your cameraout ; - but it is aswell for you tok n o w beforehandwhere to go, and toget there before thesnow surface hasbeen destroyed bytraffic.

I have spent many hours in woods anddells, roving round farms and villages inthe snow,. but I have never succeeded insecuring what I consider successful exhibi-tion result. Some of my best, or whatpleases me most, are those taken in somewoods one morning after a slight fall ofsnow. The ground was not completelycovered, and parts of the banks -and hedgeswere only sprinkled, the prints revealing avariety of tones, and not just black andwhite ; but even with these sunshine ismissing.

You' will have gathered from this thatsnow scenes are probably not very popularin photographic circles ; this may be dueto the difficulty experienced, but I believemost keen amateurs will go on trying until

' they have succeeded in getting what theywain. Therefore I would advise you to beready at the right moment. My aim is toget a snow landscape, complete with trees,fields, farmhouse or cottage, and perhapsa lane with a five -barred gate ; when I findit I shall make more than one 'exposure inorder to secure the correct picture. Thetime and stop required must be a matterof careful judgment on the spot at the time ;I shall use perhaps F6.3 and 1 -tooth, alsoFII with the same time. It will dependon the amount of white snow around andalso the value of the sun. I shall striveto keep every detail sharp, including thesurface of the snow. I would also be verycareful to correctly' develop the film andwould use Azol, because it gives soft nega-tives. I believe with stiqiii conditions 'I couldmake a good picture on a normal 'grade ofbromide paper, such as Barnet, Gevaert orIlford.

Frost PicturesThere are, however, other scenes besides

snow in winter which we should look forand which are, during these months, morecommon. If you will take a stroll across

your local park or through a country laneone morning after a very hard frost andbefore the warmth from the sun has hadtime to remove the traces, you will notfail to be struck with the beauty of thebushes and twigs. These were very com-monplace yesterday, but to -day, when they'are covered with Nature's very delicate -work, they have become pictures. A youngbeech tree decorated with hoar frost is alovely sight, so also is a low, stragglingbramble bush close to the ground with stillmany of its last year's leaves. Should youknow where to find .a tamarisk bush or hedgewith its twigs covered with close, fine foliageyou should go straight to it before the frostdisappears. You may be fortunate to arrivejust when the sun is shining ion theseobjects ; then is your chance. Set thecamera for 1-5oth with F8, and make certainthe distance scale is correctly adjusted beforeyou shoot.

Many subjects similar to these can befound in your own gardens. Have you evernoticed the beautiful effects of frost on aspider's web ? I do not know where thespider goes to in winter, but I have manya time seen the beauties of his workenhanced or revealed by frost, and with moretime on my hands I intend trying to recordit on a film.

One day during January last, year Iremember seeing a bush of the thin, finetwig variety, with a mass of tiny globulesof water at each point of its foliage ; thesun had been on it sufficiently long todisperse the frost. Unfortunately I had

* exoliausted my spool, and therefore could notmake a shot, but I know now where to finda picture.

I cannot leave this feature without makingreference to the,,, frost pictures which areoccasionally to be found on our windows.I remember an old-time profesSional friendshowing me a negative which he had takenof his dining-roqm window one wintermorning over 4o years ago. In those daysall plates were slow ones, even the fastest,as compared with our present-day films, andhis largest stop was F8. The result wasa .perfect negative of a beautiful naturestudy.Frozen Ponds and Lakes

There is still one other feature of winterwhich we can at times use in connectionwith our hobby, and that is ice. We mustpass over any detailed description of iciclesand their possibilities for picture making, inorder to devote a few lines to frozen pondsand lakes. Perhaps you have in your localpark a lake or small ornamental water.. Ihope it has natural banks, and by this Imean not artificial sides made of cementand stonework. Perhaps there are somewaterfowl. Have you ever noted what acurious effect -is prOduced when ducks orother fowl are walking on a sheet of ice ?You can also get some charming studiesarouhd this lake when there has been aslight fall of snow leaving the trees, bushesand banks slightly covered ; but wait forthat splash of sunlight.

Should the frost continue long enough,skating may be _permitted on the lake orriver ; this should offer you the chance ofgetting some very different type, of pictures.If you have a friend who can skate well,you should try a shot or two in an " action "picture. Use an open stop, if possible F5.6or F6.4 with a fast film.


Diesel or Petrol ?

AR conditions have imposed interestingchanges- on the direction of progressin prime movers.. Up to 1939 there

were, clear signs that the diesel engine was60

© //

tr...,::-

.....0°'

2.1 4 1 6:1 8"/Mortiire Ratio with Air

Fig. 1. Effect of volatility of petrol onstarting at different mixture strengths.Commercial petrol, in winter (4 deg. G.) ;2-.Cornmercial petrol in summer (20 deg. C.);3-netizole-petrol mixture, in winter (4 deg. C.);4-Benzole-petrol mixture in summer (zo deg. C.).

/0"/

.A Future Problem for Power EngineersBy C. 0. LLOYD

former is less, against which can be set thebetter flexibility of petrol. Then, again, adiesel engine is usually more expensive thana petrol engine, but offers the advantagesof lower fuel costs and greater robustness.Indeed, one can draw up a list of thecharacteristic advantages and disadvantagesof petrol and fuel oil, and still be dividedon the opinion as to the better source ofpower. The ultimate criterion depends onthe purt5ose for which the engine is required.For large stationary units there can be littledoubt that the oil engine is the correctchoice, but the lower one descends in thepower output scale the 'more problematicaldoes the question become. The petrolengine Ms the advantage of lower stressing

encroaching on the field of the petrol engine,where the latter had held sole sway, as,for example, in light transport. In themeantime the issues have become morecomplicated, and where one would haveexpected progress there has been retrogres-sion, due, no doubt, to the artificialconditions imposed by the war. It is not,however, sufficient to explain awayunexpected developments by ascribing themto " artificial " conditions. Many of the newfactors imposed on industry of that day bythe last war not only remained, but servedas a' springboard for further developmentsof an unexpected nature.

To -day, crankless engines, turbine -drivensuperchargers and jet propulsion are beingdiscussed freely, and the indications are that'there is something more than merediscussion in the air. This is an exampleof what might happen to prime movers inthe future, although one must weigh up allrelevant information before drawing conclu-sions. The more spectacular part played byaircraft_ may mislead one into .thinking thatthe petrol engine has established itself onceand for all in that sphere. There is atendency to overlook the part played by,fueloil on ground mechanical equipment and thesteady progress. being made, while thechanges in industry are perhaps morepermanent and significant.

Petrol and Fuel Oil ComparedThere are, of course, the well-known

differences between fuel oil and petrol asa source of power. The fire hazard of the

/00

.1 90

80

Petrel

Gas

These/

Eingele Sorer/ -11.-

Fig. 5.-Mechanical efficiency of petrol, dieseland gas engine compared. (judge.)

459 0 ,0 /200 /600 2000 2400 2800 .3200Punning Speed, RPM

Fig. 2.-Variation of volumetric efficiency ofdiesel engine with speed. (Ricardo and Glyde.)

0 so

70

60

and greater simplicity in design, so makingit a lighter job and, therefore, more suitablefor' Mobile work where weight is a maimconsideration. Diesel enthusiasts willmaintain that wear and upkeep arelower for the diesel, but this is notnecessarily 'so in high-speed diesel enginesof lower -power rating, although with carefulusage there may be a little in favour of thediesel in the above two respects.

(20

so

..... .........".4%.,k''.....

Diesel..;...,,......'"........ j..4.

Pens le % ..,"....."%%4

400 800 /200 /600. 2000 2400 2,800

Fig. 3.-Variation of e R

PM-

Fig. for a- dieselengine, with engine speed. (Ricardo and Glyde.)

Some Modern ComparisonsThe last decade has proved fruitful from

the point of view of fundamental andpractical research on engine -fuels. If oneconsiders that the thermal efficiencies ofdiesel and petrol engines are similar, andaround 3o per cent., one can expect mostimprovement to come from the fuel itself.This has happened in particular with petrol,improvements in jets, cylinder heads andother parts having perhaps been more inevidence with compression ignition enginesas contributing to progress, rather thanstartling developments in fuel oil. Thetendency with the ca. engine is to look formethods_ of ,using uder oils rather thanto step up the quality of the fuel. On theother hand, every effort has been made toimprove petrol, particularly its anti -knockqualities.

VolatilityThe ease of starting in an engine is

measured by the volatility of the fuel, other

'1" 60

things being equal. Thus the lower theboiling point of petrol, the quicker the start,but owing to the widely different nature ofthe fuels and the engines in which they arc

14

2

,0

t 8r.

MechanicalEfficiency -

H4drisceaf7,gfwer

BrakeHorse Power

Frictioil Loss,

700

/00,E

90

80 it

20 .....,

40/0

900 /100 -

Fig. 4.-Relanon between engine speeds,efficiency and power output.

employed it is not possible to comparepetrol and fuel oil.. W. A. Whatmoughshowed in 1933 what improvement can beeffected in starting by using the right petrol,Fig. r being plotted from his data. The,influence of air temperature is clearlyrevealed- in the steeper slope of the curvesfor winter fuels ; that is to say, the, reductionof volatility of the petrol which accompaniescolder weather.

Engine SpeedThe larger field for the diesel is that of

the low -speed stationary unit, where,unquestionably, this type of prime mover hasproved as important a step in industrialprogress as the steam engine. There is an,optimum speed where the volumetricefficiency is abbut 8o per cent. Scavengingand attention to. details have made for furtherimprovements, but Fig. 2, due 'to Ricardoand Glyde, illustrates this aspect well. Withvolumetric efficiency goes power output, anda comparison on this, between a petrol anddiesel engine, has been made by the sametwo engineers, and is given in Fig. 3. Itwill' be noted that the diesel offers' bettertorque -speed characteristics over a widerange, but between goo and 1,600 r.p.m. thepetrol engine is superior.

Mechanical EfficiencyThe practical engineer wants to know

what power yield he is going to obtain froman engine for a particular fuel expenditure.One cannot decide from thermal efficiencyor factors other than mechanical efficiency,which, in effect, informs the user what power

4

CL

60 65 70 75 80Octane Nsisber

85 .90

Fig. 6.-Loss in power due to fall in octanerating of a petrol.


return he is getting. This raises a pointwhich in turn means that the suitability orotherwise of a power unit can only be°decided with reference to the work for whichthat unit is required. Fig. 4 emphasises thisWell, showing as it does the connection.between engine speed, power output andmechanical efficiency. The results shownmay be said to be typical of all high-speedengines, and closer examination of theB.H.P. curve reveals that there is a tendency,for this particular engine at least, to dropslightly in efficiency above 1,100 r.p.m. Thecurve for mechanical efficiency is derived bycombining the B.H.P. and friction losses.

The importance of running speed is againemphasised by the comparison of mechanicalefficiencies between a gas, petrol and dieselengine given in Fig. 5. The steady declinein efficiency with engine speed is apparentwith all types, but it is =cresting to notethe wider speed range of petrol units.

It is evident from what has been 'saidabove that no generalisation can be madewith regard to the best type of prime moverfor a particular job. The availability of, fuelhas, furthermore, to be considered. Forexample, if gas is plentiful a gas engine isthe obvious choice, provided, of course, itscharacteristics are suited to the work.

Power Rating and SpeedInduitrial experience has largely influ-

enced the progress of certain units, so that

it is possible to group diesel and petrolengines thus :

POWERREQUIRED ENGINE SPEED TYPE,

1-50 h.p.

00-100 h.p.

100-200 h.p.

300 h.p. upwards

Up to 4,000 r.p.m.

2,800-3,000 r.p.m.

2,4011-2,500 r.p.m.

Low Speed Dieselsor Gas Engines

Petrol

Petrol or'HighSpeed Diesel

Petrol or HighSpeed Diesel

Fuels.Many invesegations have been made into

the behaviour of fuels in the cylinder ofan engine. Theory combined with practice,in which the physicist, engineer and chemisthave -collaborated, has served to unravelmany of the mysteries of combustion.X-rays, spectrographs, cathode ray tubes areonly some of the instruments employed inthis research work, which has madeconsiderable progress in the last ten years.An exact record, for example, of -thedevelopment of the combustion,. wave frontin a cylinder has been made detonation hasbeen examined, and, aoVe all, thisknowledge applied to practical ends, so thatfuels are not only better but cheaper,excluding war influences.

Fuels have been graded in knock rating,or their lack of tendency to deteriorate athigher compression ratios. This isimportant, inasmuch as higher compressionratios mean greater power output and

efficiency. This fact has been so evidentwith designers of petrol engines ,that suchunits are now operating at compressions nearthe lower values for diesel engines, owingto high octane fuel. '

Incidentally, a petrol is usually rated withreference to octane, while diesel fuel ismeasured in terms of cetene, which is alsoa liquid ,hydrocarbon. In the past few yearsmore attention has been paid to the cetencnumber of fuel oils, a significant point. Theinfluence of octane number on the powerloss from a petrol engine has been recordedby L. E. Hebl and T. B. RendelMay, 1939) as in Fig. 6. The diesel pictureis brought up to date by the Report of theDiesel Fuels Division of the Co-operativeFuel Research Committee of the UnitedStates (J.S.A.E., February, 1941), in whichit is stated that a high cetene value improvesstarting, idling and the power yield on lightloads,. while this factor is also consideredto give maximum piston ring life beforesticking.

The war has interrupted much develop-ment and research to find a better dieseland petrol engine for general use. It hasalso- served to give progress an abnormaltwist, so that one should not take presenttrends too literally. The point at issuewould seem to be whether smaller dieselscan cover the field ,requirement of the petroland whether there is room for larger petrolengines where medium diesels are nowemployed.

LettersRUNNING CARS ON " CALOR " GASSIR,-With reference to the reply to Mr.

S. T. Jones, of Leominster, in Queriesand Enquiries of the August issue ofPRACTICAL MECHANICS.

The running of cars on " Calor " gas, andother propane 'and butane mixtures, is no

'novelty. In 1940 it was possible to have acomplete installation for the sum of £12.This including the mounting of the gascylinder, fitting of a flap valve to the car-buretter intake, and a tap system. Thesupplier being Carbuettors, Limited, GrangeRoad, Willesden Green, London, N.W.to.

Calor gas liquefies at 221b. per sq. inch.It is supplied to the carburettor, via areducing valve, at a pressure of 41b. Per-formance on Calor gas is almost equal tothat of petrol. Starting, acceleration, andclimbing power all being good.

Running costs rather higher than petrol.A cylinder being sufficient for approximately150 miles on a to h.p. car. The cost for arecharge, in 1940, being 16s. Advantagesover petrol are : Freedom from detonation(no pinking) and absence of oil dilution.

Everything appears all right, but, of course,there is a snag. The suppliers of propane/butane mixtures were not willing to supplygas for motor vehicle propulsion. But if youcan obtain the gas, it is the best alternativeto petrol yet discovered, and it is definitelypractical.

A. E. LEECH (West Molesey).

DISSOLVING FILM NEGATIVESIR.-In the reply to a Blackpool reader's

query in the November issue ofPRACTICAL MECHANICS, it is suggested thathis difficulty in dissolving portions of anundeveloped film negative in 'a mixture ofamyl acetate and acetone was probably dueto his failure to remove the gelatine coatingon the film.

This may be so, but it is also possible thatthe film was of the " non-flam." type

from Readers(cellulose acetate, I believe). This is cer-tainly not readily soluble in amyl acetate andacetone, but there is one good solvent avail-able, diethylene dioxide (dioxane). Quite agood, thick cement can be made overnight,or even in a shorter period of time, bydissolving small pieces of X-ray or otherfilm in this fluid, which also dissolvesordinary cellulose very readily.

Incidentally, to remove the gelatine coat-ing from used film, particularly if the filmhas been " fixed " in an acid hypo bath, orhas been acid hardened, it is generallynecessary to use more than hot water. Evenboiling in water sometimes fails to dislodgethe obstinate gelatine. But soaking in ahot solution of soda (preferably caustic) forsome time usually does the trick. Even ifthe gelatine is not Completely dissolved, itwipes off easily with the fingers, leaving aparticularly clear piece of celluloid, whichafterwards wants thorough washing in wateronly.

J. P. NAPPER (Cardiff).

ELECTRICALLY DRIVEN MODELRAILWAY

SIR,-In a recent issue a correspondent,Mr. J. K. Dixon, asks about a method

of electrically driving an 8in. gauge railway.For four years I have been running a

win. gauge line by a method which maybe of interest. An A.C. motor on the housesupply, i h.p. in my case, drives a 12 -voltmotor -car dynamo, 95o r.p.m. is fast enough,This supplies current.pt 25-35 volts, 8 -toamps. ' to a six -volt small car dynamoreconnected with the field coilein parallel asa series motor. This is fitted to a " tram "meant to carry two children at a time, butcapable of more, at 4 m.p.h. on a stickytrack.

A motor -car cut-out must be wired in toreduce the dynamo voltage on open circuitby a series resistance.

The merit of this system is that all the

components are easy to obtain, and norewinding of motors or dynamos is needed,while an accumulator charging outfit isthrown in for the price of an additionalcut-out from an old car.

R. B. T. HALL-CRAGGS (Hale).

I,ELECTRON MICROSCOPESIR,-I was very interested to note in the

October issue of PRACTICAL MECHANICS(p. 33) that Mr. R. S. Trowel, of Newport,Isle of Wight, proposes to build an electronmicroscope.

The following references may be of useto him: journal of Biological Chemistry,1942, 146, 25 ; British Medical Journal,1942, 2, 728. There have also been somepapers in recent issues of the Journal ofBacteriology. He should be able to consultthese journals in the British Museum, orpossibly in the loCal Public Library.

I am quite willing to obtain any furtherinformation from the published literaturehe may require.

J. 0. DAWSON (West Bridgford).

A New Vest Pocket -book

SCREW THREADTABLES

By F. J. 4C A M M

(Editor of Practical Engineering)

214 pages ; fully indexed and illustrated,and including a section on change -wheelcalculations.

51-, or 513 by post from

George Newnes, Ltd., Tower House,Southampton Street, Strand, London,

W.C.2.


QUERIEScviaENQUIRIESA stamped addressed envelope, three pennystamps, and the query coupon from the currentissue, which appears on back cover must be enclosedwith every letter containing a query. Everyquery and drawing which is' sent must bear thename and address of the reader. Send yourqueries to the Editor, PRACTICAL MECHANICS,Geo. Newnes, Ltd.; Tower House, Southampton

Street, Strand, London; W:C.2.

Speeds for TurningWILL you please answer the following

questions :At what speed should a 3 jn. lathe travel for

turning 4in. round cast iron, sin round mildsteel, in, round brass.

I tried turning the cast iron and the tool simplyturned up at the attempt, yet it turned the mildsteel. So I wondered if I had too many r.p.m.on the lathe, which is driven by a h.p. motor at1,450 r.p.m.-J. C. jobson (Grimsby).THE speeds for the sizes specified are, using high-

speed steel tools :4in. cast iron, 5o r.p.m. roughing, 70 finishing.tin. mild steel, 190 r.p.m. roughing, 400 finishing.'in. brass, i,000 r.p.m. roughing, 1,92o finishing.The reason for the tool turning up is that it is too

keen. The top rake for cast iron ',Should be only abouthalf that for mild steel.

Element holders for Electric FiresT AM anxious to experiment in making " clay "-I element plates or holders that are used inelectric fires and boiling rings, on which the wireelement is wound. Could you tell me what theconstituents of this " clay " are : in what propor-tion they should be mixed, and how they shouldbe made up ? I would also be glad if you couldtell me where I could purchase the necessarymaterials and if there is a commercially, madeproduct which would answer my requirements ?-R. Drohan (Kilkenny).THE electric elements to which you refer are merely

unglazed porcelain, prepared from a mixture ofsuitable China clays. To make such elements, yourequire a muffle furnace capable of attaining a hightemperature. Given this,- the elements are mouldedfrom a mixture of roo parts China clay and ro partslimestone, together with about r part soda ash, afterwhich they are baked for several hours at a nearlywhite heat.

We imagine that you will not find it possible to carryout such a process; however, these electrical "porcelainformers " can usually be obtained from any largesupplier of electrical fittings.

Rubber Latex

I:T HAVE recently been experimenting with

latex liquid rubber on shoes for re -soling.I have used carbon, sulphur plastic, etc., with itfor a " filling " material but with no success.

Can you tell me how to crepe, the rubber and'make it stick to the old soles, or give me analternate filling medium as used in car tyres ?-G. Armitage (Selby).

YOU will find it a very difficult job to make rubbersoles unless you possess a good knowledge of

rubber technology. . It is not possible to make sucharticles merely with the aid of rubber latex, since it'any attempt is made merely to " fill " the latex, the latterat once coagulates and loses its characteristic properties.The best filling " agent for rubber latex is ordinaryPortland cement. This gives a rubbery sort of concrete,but such a product is more or less brittle and is, ofcourse, entirely unsuitable for adaptation to footwearrequirements.

The following is a typical formula for the makingof a rubber suitable for soles. Like all these rubber" mixes," however, it has to bp cured for a definitetime under steam pressure. Hence its use will necessitatesome steam pressure apparatus in which the mixturecan be exposed to steam for the requisite time :

Sheet rubber (or dried latex) .. 5 parts.Scrap rubber powder .. 54Dried clay (fine)Zinc oxide .. 1

Red iron oxide .. . . 4 3

DiphenylguanilineSulphur ..

Cure for seven minutes at a steam pressure of 6olbs.sq. in.

For sticking rubber to old soles, use a thick solutionof rubber in naphtha. A very small amount per cent.)of bitumen dissolved in the same solution increasesthe tackiness of the mixture.

It is, however, absolutely impossible for an amateurto produce a processed rubber similar to that employedin the making of car tyres, since not only are theserubbers " cured " at high steam pressures, but alsothe majority of them are of more or less secretcompositions.

Insulating Medium for RefrigeratorT AM making a domestic refrigerator, and shallA be glad to have your opinion as to which is -the best insulating medium. I was contemplatingusing granulated and slab, cork, but a few testscarried out proved unsatisfactory.-L. Walker(Mill Hill).YOU do ,not indicate exactly what type of domestic

refrigerator you are making, nor do you give usany indication of its size. We presume, however, thatyour refrigerator is of the " ice box " type. For such apurpose we see no reason why granulated cork (notslab or compressed cork) should not prove perfectlysatisfactory.

Alternative non -conducting materials are asbestosfibre, kapok, hair and dried seaweed.

We suggest that you employ as a heat -insulatingmaterial a mixture of granulated cork and coarse fibreasbestos. These materials can be obtained from theunder -mentioned suppliers, but we do no( think kapok,hair or seaweed are available at the present time.

Cork suppliers : Messrs. Henry Bucknall and Sons,Ltd 90, Fenchurch Street, London, E.C.3.

Asbestos suppliers : Bell's Asbestos and EngineeringSupplies, Ltd., Slough,' Bucks ; Turner BrothersAsbestos Co., Ltd., Rochdale.

Ammonia : Chemical. Action on Metals(7.) CAN you tell me the reason why purek, -V -ammonia has a chemical action againstcopper, brass and solder, turning the liquid blue ?

(2) Is there any acid or liquid that I could mixwith it so as not to affect the strength of theammonia ?-K. A. Varey (York).(.,,.` IT is impossible for us to tell you exactly why

ammonia attacks copper, brass and other metals.You might as well demand to know precisely whyoxygen combines with some metals at red heat andnitrogen does not. However, the reason for the bluesolution formed when ammonia attacks brass, copperand copper -containing alloys is to be seen in the factthat all chemical solutions containing copper, are blueor bluish -green in colour, and that ammonia, througha complex chemical mechanism, forms such solutionswhen it attacks copper. These blue solutions consistfor the most part of solutions of copper hydroxidecombined with the ammonium radical, but they arealways of varying composition.

(2) There is no acid or liquid which you couldmix with ammonia to prevent its attacking copper.Indeed, if you did mix an acid with ammonia the latterwould immediately be neutralised with great violenceby the ammonia. There is no liquid known whichwould have the effect you seek.

Preserving Worm-eaten Wood : NitrogenIodide

IS there any method of preserving worm-', /J eaten wood ? The insect is a small, white,soft grub similar to the maggot found in cheese.I wish to kill it in plywood panels indoors, in whichit has already bored many holes. I think it mightbe the larva of the Death Watch beetle, especiallyas I heard a faint ticking noise in another roomover a year ago. It was like the ticking of a watch,but stopped and started at about 30 secondintervals. Is creosoting the backs of the panels,or painting them with lysol, or a solution ofcopper sulphate, any use ? Our house is entirelybuilt of wood, and the outside and roof arecreosoted regularly.

(2) Also, can you tell me the cheapest methodof preparing nitrogen. iodide ?-A. Andrew(Larbert).(..." THE worm holes which you describe areA) undoubtedly made by the Death Watch beetle,

although it is somewhat unusual for this beetle toattack plywood ,on account of the bonding agentspresent between the layers of wood.

The complete eradication of the Death Watchbeetle is not an easy matter. It calls for muchdetermination and patience, and, also, a clear knowledgeof the habits of the beetle and its larva. The beetleemerges from the wood between April and July of theyear. After mating, it lays its eggs in tiny crevices inthe wood. The eggs hatch out in August, and theyoung larvae immediately penetrate into the wood.They remain active in the wood for usually two years,

that is to say, until the next Spring but one subsequentto their hatching. About March of that year the larvatunnel to about lin. or (in. from the surface of thewood. Here they form chrysalises, and, after a weekor two turn into the adult beetles, which soon aftereat their way out of the wood, forming the characteristiccircular holes. These again lay eggs on other portionsof woodwork, and since the beetles are able to fly thedamage is readily spread about.

Your best plan for dealing with the problem is towait until the March of next year. Then apply hotcreosote liberally to the woodwork, and subsequentlykeep up weekly applications of hot paraffin or naphthaevery fortnight until the end of July. This treatmentwill kill all beetles on or before emerging, and it willprevent any egg -laying. The same treatment shouldbe applied in the following year at approximately thesame period in order to make sure of a complete cure.

It is vitally necessary to apply the above liquids ashot as possible in order to ensure their efficient penetra-tion of the wood.

You will, of course, 'remember that you cannotpaint over creosoted surfaces. Hence, if the wood hasto be varnished or finished in any way do not usecreosote, but employ naphtha instead.

One _pound of ortho-dichlorbenzene and ilb. ofzinc naphthenate dissolved in a gallon of naphthamakes an excellent solution to eradicating DeathWatch beetle, provided it is applied at the above timesof the year. These materials may' be obtained fromMessrs. A. Boake, Roberts & Co., Ltd., Stratford,London, E.t5. Such a solution is non -staining, andmay he safely applied even to _furniture.

Water solutions of cooper sulphate, etc. are usuallyof little use for the above wood treatment, because theydo not effectively penetrate the wood.

(2) Since nitrogen iodide is a very highly dangeroussubstance, to produce, we feel that we must ask youto excuse us from giving the details of its making.Doubtlesa, however, you might be able to get suchdetails from any advanced textbook of inorganicchemistry.

Copper -Plating SolutionCAN you please help me with the folloying

queries :What are the proportions for a copper electro-

plating solution ? What are suitable currentdensities per sq. in. of deposit collecting area,and . solution temperatures for (a) copper -plating, and (b) nickel -plating ?

Can a copper body ;r3.2in. thick be successfullybuilt up on a thin metal foil by means of electro-plating ?-W. Moughtin (Billericay).ASIMPLE and 'effective copper -plating solution is

made up as follows : Copper sulphate, 11 -alb.sulphuric acid, 4-6 ozs. ; water, r gallon.

This bath is best operated at normal temperatures,or at a temperature slightly above this, say, at 25 deg. C.It is best worked with a" current density of 25-3oamperes per sq. ft. of deposit area.

A small amount (say, per cent.) of glue or gelatineadded to the bath sometimes results in a better anda brighter deposit being obtained. Sometimes, also,a trace of photographers' hypo " (sodium thiosulphate)ris added to the bath for this purpose.

The following is an effective nickel -plating bathNickel ammonium sulphate, 12 ozs. ; water, t gallon.

This bath is operated at normal temperatures and _with a current density of 4 amps. per sq. ft. Its rate ofdeposition is slow, but the deposited metal is very hardand fine -textured.

You can build up a copper body on a metal foil byusing the above copper bath. In such an instance itwould be preferable to increase the acid content of thebath, to raise the current density, and also to agitate thesolution continuously during the plating.

Space RocketsT AM interested in the development of the liquid

fuel rocket, and hope to carry out someexperiments in my workshop.

Can you answer the following queries on thesubject

(t) Of what material are the combustionchambers constructed ?

(2) The fuel which'. I believe consists of liquidoxygen and hydrogen discharged from separatejets has to be mixed in certain proportions-canyou tell me what these are, and also if the fuels

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140

ignite on contact with each other, or if they arestarted burning by some other means ?

(3) How can I calculate the lift provided by agiven combustion chamber and expansion nozzle ?

(4) Can you recommend any books on the subjectof Astronautics, and also give the address ofBritish Interplanetary Society.-R. W. Boggio(Walton -on -Thames).

(t and 2) Very few so-called space rockets 'haveever been actually constructed. Those which have -been made experimentally have had cases of lightsteel or of aluminium, the combustion chambers beingmade of either of these metals, usually the former.

It has usually been proposed to propel such :rocketsby, means of successive charges of a suitable rocketpowder of the gunpowder type. At times, however,it has also been proposed to employ liquid -air Soroxygen) as a propellent merely by the rapid gasificationof these liquids and their consequent expansion.Liquid hydrogen ha;; not been used, although it hasbeen suggested as a means of increasing a rocket'senergy of flight.

(3) You cannot calculate the life which would begiven to a rocket merely from a consideration of thedimensions of its combustion chamber and expansionnozzle. The entire design, dimensions and weight ofthe rocket profoundly modify its " lift " "and until allthese factors have been taken into consideration, anycalculation of the natute you require iy more or lessout of the question.

(4) The entire subject of interplanetary communicationis very nebultrus at the present moment. The BritishInterplanetary Society has, we believe; disbanded (atleast tem'porarily), and there are no practical formula:relating to the design of rockets on the lines you require.A few books on the proposed interplanetary travel havebeen published, the more serious and thoughtful onesin America. If you will write to Messrs. W. & G. Foyle,Ltd., Booksellers, Charing Cross Road, London, W.C.z,they will, we think, bd pleased to give you the titlesand prices of any such books which may still be available.They will also advise you if they happen to have anysecond-hand books on this subject in stock. Youshould also refer to your local Librarian and inquireas to whether any such volumes can be procured onyour behalf.

CeriumCAN you give me any information about

cerium and, if possible, the details ofmanufacture and Where obtainable.-F. Rodgers(Bolton).'L'OR 'a detailed description of cerium, -its properties-1; and production, we must refer you to an up-to-datechemical work auch as J. W. Mellor's " ComprehensiveTextbook of Inorganic Chemistry," a copy of which,we think, is in the Bolton Library, and which is certainto be in the Manchester Reference Library.

Within the space of a short reply, it is only possible'for us to give you a very brief indication of the natureof cerium.

Cerium is a greyish, hard metal which is soluble inacids but which remains substantially unoxidised whenexposed to air. It alloys readily with iron. It is apyrophoric, that is to, ay, a spark -producing metal, andit is on account of this fact that it is now being'producedfor war purposes. Cerium alloy forms the flints " ofpetrol lighters, and other spark producing devices.

The' pyrophoric nature of cerium and its alloys wasfirst discovered- by Dr. Carl Auer, Baron von Welsbach,of Berlin.

Cerium nowadays is derived from rare -metal -earths.From these, a complex alloy known as " mischmetal "is produced, this being derived from rare earths whichwere once- a by-product of the gas -mantle industry.The earths are converted into chlorides by treatmentwith hydrochloric acid. Then they are mixed withcalcium chloride and electrolysed. In this manner,the alloy, " mischmetal " is produced. It contains5o per cent. of cerium. For pyrophoric purposes, this'*Hoy is further alloyed with iron and then cast intosmall rods or other convenient formations.

For the preparation of pure cerium, chemical and/orelectrolytical methods -can be used, but these are allvery tedious and complex, and for their detaileddescription, we must refer you to a standard work ofreference, such as the above -mentioned book.

Cleaning Used OilT UNDERS'PAND it is possible to make up a.1- composition to clean used lubricating oil.

Is this correct, and if so, what are the chemicals,and where can they be purchased ?-R. T. Calver(Gt. Holland).APART from the process of chemical refining, which

involves treating the oil with strong acids andalkalis, and subsequent distillation, there 4s nosatisfactory method of cleaning oil merely by treatingit with a composition."

The best way to purify used oil to some extent isto filter' it through a " rough " filter, such as a pieceof muslin or similar coarse -weave fabric, and, afterwards,to allow the filtered oil to- percolate through activatedcharcoal or through activated alumina. After percolationthrough either of these materials, the oil should be fitfor use again.

The charcoal or alumina' is purchased in the formof coarse grains, and it is packed loosely into a cylindersuch as a tlb. coffee tin provided with suitable exitholes at its base. The oil is allowed to seep through this,the whole apparatus being kept fairly warm in orderthat the oil may not be too viscous. Naturally, thewhole operation is a slow one, but, in most instances,this is no disadvantage.

It is doubtful whether you will be able to procure

NEWNES PRACTICAL- MECHANICSactivated charcoal at the ptesent time, but activatedalumina (aluminium oxide) is still obtainable fromMessrs. Peter Spence & Co., Ltd., Widnes. It canbe obtained in varying grades of fineness.

]Magnetic CoilsWOULD you please let me know the formula

for magnetism, both A.C. and D.C. current ?By that, I mean, for a given core area of an electro-magnet, and voltage, current, gauge of wiretaken into, consideration. How many turns ofwire will be needed to bring the electro-magnetup to its maximum efficiency ?-F. Scholfield(Rotherham).TT is not possible to give a simple formula for magnetic41 coils as there are many factors to be taken innsconsideration in individual cases, and designers spenda considerable amount of time in arriving at the mostefficient coils for various purposes.

With D.C. coils, for example, the permeability ofthe iron core governs the number of ampere turnsrequired to create a magnetic field of a given strength.The permeability varies with different types of ironand also is not a constant factor as it varies with themagnetic flux density in the iron. For some purposesit may be best to use a small core which is wellsaturated with magnetism so that the permeability islow and a relatively large number of ampere turns arerequired, rather than use a large core at low magneticdensity and high permeability which requires arelatively small number of ampere turns. -With goodquality of iron it is usual to work at about 13,0oo linesof magnetic force per sq. cm. Above this density, withgood quality iron, the permeability falls fairly rapidly.

Having decided on the magnetic density to be adoptedand knowing the total field strength required, it is asimple matter to calculate the cross-sectional area ofcore required. Magnetisation curves then give thenumber of ampere turns' needed to create the requiredmagnetic density per unit length of iron circuit sothat the total ampere turns can be calculated. Ifthere is an air gap in the iron circuit the number ofampere turns required to pass the magnetism acrossthe gap may be as high as 13,000 times that necessaryfor a similar length of iron circuit. If the iron circuitis of non -uniform cross-section the ampere turns foreach section having different magnetic density will becalculated separately and totalled up.

On a shunt coil which is fed from a constant voltagesupply the required ampere turns will be providedby a large number of turns of small gauge wire of hightotal resistance so that a small current will be required.If the coil is a series coil carrying a high current thecurrent may be a fixed quantity so that the numberof turns will also be fixed.

In the ease of A.C. current the calculations becomemore involved owing- to the losses set up by eddyqurrent in the iron resulting from the changing magneticflux, and the fact that the 'current through the coil iscontrolled by its reactance as well as its resistance;the reactance will depend on the magnetic flux linkedwith the turns and upon the frequency of the supply.The querist is ,advised to study one or two books whichdeal with the subject of electro-magnetism in detail.

Cur Starter as A.C. MotorT HAVE a 12 -volt car starter motor which I wishA. to convert to a 250 -volt A.C. motor to drivea sewing machine. The motor would require todevelop 5/25 h.p. The armature is 2fin. long,21,in. diameter, with 21 slots in. 7/ta deep and. 3/32in. wide. There are four poles and four copperbrushes. Could you please inform 'me how towind the armature, and field coils, etc. ?-T. McGhie (Scotstoun).THE type of starter -motor you describe is not

altogether suitable for use as a high -voltagemains motor, as the thicker insulation required inarmature slots and oilfield poles leaves very little room foractive conductors. Carbon brushes of Link A gradealso should be substituted for copper brushes. Sincethe power output required for sewing machine drivesis so small, you may, possibly obtain what you requireby re -winding as follows : Armature, 21 coils, eachcontaining 85 turns of No. 35 d.s.c. copper,coil span froth slot t to slot 5 inclusive, wave -connectedto 2i -part commutator; fields, four coils, each with600 turns 'of No. 29 s.w.g. d.s.c. copper connected inseries with armature, interconnected to give alternatenorth and south polarity. The thickness of insulationshould not be less than 15 mil. empire cloth or leatheroid,

Curing Rabbit SkinsT HAVE heard that there is a simple method ofA curing air-dried rabbit skins. Can you giveme details of this process ? Will a skin- dressedor cured by this method remain pliable, or willit stiffen after a time ?-D. Barlow (Walsall).IN order to cure a 'rabbit skin, first of all scrape the

inner side of the skin with a blunt knife in orderto remove every trace of .Nash and loose tissue. It isconvenient to do this by stretching the skin, fur sidedown, over a baluster rail or some similar curved.object.

Then dissolve 4 parts common alum and I partcommon salt in 8 -to xo parts of water. Immerse theskin in this solution for about 48 hours. In order toascertain whether the skin has been soakeij long enough,squeeze the liquid from it and then double the skinup with the skin side outwards in order to make a sharpcrease. If the latter shows white and clean, the soakinghas been completed.

After the skin's immersion in the salt -alum bath,rinse it well and then rub over it a paste made of flour

January, 1944and water or oatmeal and water. Work the pastewell into the skin, and then wash it all off. .

The skin should now be stretched on a board andallowed to dry slowly in the air. The skin will dry'hard, but it can be softened by constant rubbing andkneading between the fingers, this action serving toinduce permanent pliability. If desired, a very smallamount of neatsfoot pil may be rubbed into the skinto soften it. However, if this is overdone the skinwill become tacky and the oil will spoil the fur.

" Flash" Paper-ypu please tell me of a substance that,

when chemically treated, will produce abrilliant flash when ignited by an ordinary x.5volt gaslighter element ? I have thought of the" Flash -paper " usually found in indoor fireworksbut am not certain of the formula. I believe it isnitric acid and sulphuric acid.-A. F. Wyer(Kidderminster).THE type of " flash paper " which you desire can be

made in the following way :Mix 4 volumes Of concentrated sulphuriC acid with

x volume, of strong nitric acid. Pour the sulphuric acid.into the nitric acid and not vice versa. After the mixedacids have cooled, immerse in them a number of ordinarycigarette papers or of paper strips of similar thickness.Allow these papers to remain immersed for three days.Then remove them and wash them most thoroughlyfor at least two hours in running water, in order toremove every possible trace of the acid.

The papers should now be allowed to dry slowly inthe air. The cellulose of which the papers is composedwill, by this process, have been changed into cellulosehexa-nitrate, or gun -cotton. As such, it will bumaway almost instantly with a flash when ignited with ahot wire, such as you mention, or with a lighted cigaretteend. "

You should bear in mind the fact that these papersare not 'without danger. Cellulose hexa-nitrate (gun-cotton) when struck, can explode very violently.Hence, it is always highly advisable to retain thesepapers in a damped condition and to- dry them in theair just before they are required for use.

Plating Formula : " Pickling"CAN you give me any information on the

following subjects. What are the formula:for -(x) Nickel and copper plating and polishing ?(2) What quantity of caustic soda is needed to

a gallon of water for a soda dip ? Does the solu-tion have to boil, and how long does one leavethe articles in to clean ?

(3) When articles are pickled in a solution ofacids, how long are they left in ?

(4) I have a glass tank 12in. x 8in. x izin. withtwo nickel anodes, one at each end, and I findthat the article being plated gets burnt. Is itbecause the object being plated is too small, orare the anodes too near the object ?-R. H. Brett(Broomfield).

(1) The following are well -tried nickel and copperplating fortmilx :

Nickel Plating.Nickel ammonium sulphate .. 8oz.Nickel sulphate .. 4oz.Boric acid _ zoz.

- Common salt .. soz.Water .. r gallon.

Operate the above bath at 80 deg. F. Use a currentof 6-8 amperes per square foot of surface to be plated,and a voltage of 2-2, nickel anode.Copper Plating

Copper sulphate tryst... 28oz.Conc. sulphuric acid .. 3-5oz.Water I gallon.

Operate the above at 75 deg. C. Use a current of10 -Is amperes per square foot of surface to be plated,and a voltage of Ps. If the solution is continuallystirred or agitated, a higher amperage can be used forquicker results, if desired, but in most instances thisis not necessary. Use anode of rolled copper.

(z) The strength of the soda dip to which you referdepends entirely upon the class of work for which youintend to use it. Ordinarily speaking, 'lb. of com-mercial caustic soda (sodium hydroxide) to the gallonof water makes a very effective solution for cleaningand degreasing. Such a solution can be used eitherhot or cold, it being naturally more potent in the hotcondition. The time of immersion of the article in thesoda dip is, again, entirely dependent upon (a) thestrength- of the dip, and (b) the extent to which thearticle in question requires cleaning or degreasing.On an average, 5 or to minutes' immersion shouldsuffice.

(3) To some extent, this question is answered in the' above reply. The. duration of " pickling " in an acidor mixture of acids is entirely dependent upon thenature of the acids, their strength, their temperature,and the extent to which " pickling " is required.Owing to these variable factors, it is really impossiblefor us to state any definite duration of pickling, for theparticular reason that We do not know the ant class ofwork to which you refer.

(4) Your nickel plating work may be "burnt " forseveral reasons, which only you yourself can ascertainby means of experiment. The reason for the " burning"may be : (a) Incorrect composition of electrolyte;(b) Too high a temperature-, (c) Too heavy a current;(d) Anode(s) being placed too near the object.

January, 1944 t4WNES PRACTICAL MECHANICS

Destruction of a Heinkel photographed from the attacking Spitfireby camera -gun. Such records are a small part of photography'sgreat contribution to the war effort. Photography is mobilized forwar, so don't blame your dealer if he says " Sold out of Selo !"Claims of the Services, Industry and Science come first. Aftervictory, Selo films will be plentiful again, faster and better thanever. Till then our chief task must be SERVICING THE WAR.

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Don't put your Cameraaway this winter. Sendfor these books

Your photography will become much moreinteresting if 'you do it all yourself. To helpyou, we will send, for 3d. in stamps, thesethree, publications. A 32 -page booklet calledHome -Photography which tells you how todevelop your own negatives, how to makeGaslight and Bromide prints, how to doFlashlight Photography and how to makeEnlargements.A folder about THE THREE PUBLICATIONSAzol, the con- WILL BE SENT TO YOU.centrated FOR 3d. IN STAMPSone = solutiondeveloper, with full Time and Temperaturetables for tank or dish development. There isalso a fully illustrated list of Chemicals, usefulsundries and accessories to help you in the work.

Special Trial Offer-For 2 3 P.O. Johnsons will send you post free (G.B. only) a trial set ofChemicals, including I -oz. bottle of AZOI., to develop eight spools 2l in.by .31in. 4 -oz. tin ACID -FIXING, making 30-60 ozs. solution, onepacket AMIDOL DEVELOPER, enough for 2 to 3 doz. bromide orcontact gaslight prints.

Be sure and address your letter to Dept. 41.

JOHNSON & SONS Manufacturing HENDON, N.W.4Chemists, Ltd.

Esfabli,lieff 1743.

E. PULL'S

WORKSHOPPRACTICE

By F. JOHNSTONE TAYLOR780 PAGES 542 ILLUSTRATIONS

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ELECTRADIXBARGAINS

POWER TRANSFORMERS.' Singlephase 50 cycles 35 KVA. 35,000 watts,by Brit. Elec. Transf. Co. 220 volts to1101110 volts, £30. 5 KVA 220 volts to5,000 volts and 500 volts, £10. 2 KVAFoster 200 volts to 4,000 volts, £8 10s.I t KVA Zenith 100 volts to 6,000 volts, LB.3 KVA 400 volts SP 50 cycles to 600 volts,oil filled, by Metvick, £9. All as new.MOTORS AND DYNAMOS. Wehave acquired a useful parcel of D.C.Motors in all sizes from 118th H.P., 116th.114th, 113rd, ' ), I, I 2, 3, 4, 5 and 6H.P., in 110, 220, and 440 volts. Thereare also a number of A.C. Motors, singleand 3 -phase, from 118th H.P. to 3 H.P.Kindly specify wants and we will offerthe nearest, as no priority is needed onthese machines.DRILLS. Electric Bench Drills, D.C.Wolf, 110 volts, massive pillar type, gearedfeed, counter weight rise. No. I morsesocket for 2in. steel. For delivery withoutpermit, £8 103. each.PORTABLE ELECTRIC DRILLS. D.C.,110 volts, £5 10s. ; A.C., 220 volts, £7 10s.PUMPS. Stuart motor pumps, centri-fugal, C.D. Shelter, 12 volts D.C. or 230volts A.C. in stock. Twin piston pumpswith or without motors, for suds or water.BLOWERS AND FANS. Exhaust andopen type of 116th to 6 H.P. available.CRYSTAL SETS. Gambrel! WIM typewith selector switch, tuning condensersand permanent crystal detector, in closedportable case, S01-. Victory Pocket typecrystal receiver, in bakelice box with oneearpiece, 351-.AERIAL WIRE, 7122 bare copper, Si-der 100ft. Lead-in wire, 4d. per yard.Aerial insulators, 2d. each.SUNDRIES. H.M.V. Resistors, glasscased, wire ends, watts, .01, .025, .05,

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" January, 1944 THE CYCLIST 25

THE

Et%)Editor : F. J. .CAMM

VOL. XII JANUARY, 1944 No. 263

Comments of the Month

The ThreeWHEN Canning was Prime Minister there

were three tailors who held a meetingin Tooley Street for the redress of populargrievances or what they conceived to bepopular grievances. They were, of course,their own personal grievances, and theyaddressed a petition to the House of Commonsbeginning : "We, the people of England,demand. . . ." The N.C.U., the R.T.T.C.and the C.T.C. find themselves to -dayin a position analogous to the threetailors of Tooley Street, over the questionof massed start racing. On other cyclingpolicy they resemble the Tooley Streettailors in that they do not speak for the

. majority of cyclists, either.We have dealt with this matter at some

length in previous issues, and we aredetermined to pursue the matter until justicehas been done. We are quite convincedthat this joint announcement would nothave been issued without promptingsfrom some of the bodies concerned,and so that our readers may form anaccurate opinion on the matter it isnecessary for us to recount certainhistory.

When the National Cyclists' Union andthe Cyclists' Touring Club were formedover zo years before the close of the lastcentury, the fastest vehicles on the roadWere horse-drawn. It was natural thatthe owners of such vehicles, as well as thecoach -building industry, should oppose thedevelopment of cycling, for cyclists werefaster than horse-drawn vehicles. Alinostevery magistrate owned a landau, a phaeton,a barouche, or a Victoria, and they wereextremely severe on any wight hauled beforethem for the heinous offence of riding abicycle. One had only in those days to beseen on a bicycle, riding sedately along acountry lane free from other traffic, to becharged with " dangerous riding," " ridingto the common danger," without considerationfor others who were on the road, or " whomight reasonably have been expected to bethere." Road racing received the attentionof the police, and so did record breaking,and much of it had to be conducted, asit still is to -day, in a hole and cornermanner, as if it were something of whichone shouldbe ashamed.

The only body then whose duty it was tocontrol road racing and to homologateattempts at records on the road, paced orunpaced, was the National Cyclists' Union.This body, instead of asking for the relaxationof the campaign of persecution indulged inby the police, as it should have done, tookthe line of least resistance, and at its annualgeneral meeting in 1888 it tabled and passedthe following resolution : " The NationalCyclists' Union, as a public body, desires todiscourage road racing, and calls upon the clubsto assist it by refusing to hold races on the roads,and it prohibits any of its officials fromofficiating or assisting at any road races, andrefuses to recognise any record made on theroads, and that this be added to the rules."

All letters should be addressed tothe Editor, " THE CYCLIST,"George Newnes, Ltd., Tower House,Southampton Street,Strand, London,

W .C.2.

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

Tailors of Tooley StreetFrom that time the N.C.U. has concerned

itself chiefly covith track racing.

Troubled WatersFOR over 5o years the N.C.U. has been

in troubled waters on questions ofcycling policy. It has muddled along andearned the censure of prominent cyclingauthorities such as George Lacy Hillier, thelate John Urry, and the late F. T. Bidlake.The latter withdrew the affiliation of theNorth Road Cycling Club to the N.C.U.as a result of its attitude towards road racingand record breaking. Bidlake was a Tritonamong the minnows.

When the N.C.U. set its face against allforms of road sport it did not kill it ; on thecontrary, it thrived, and a few months later(in April, 1888) Mr. A. J. Wilson foundedthe Road Records Association to hothologaterecords on the road.

Racing on the roads also continued, andwas controlled by a number of bodies until,a few years before the war, the Road. TimeTrials Council was formed by a number ofrebels from the old Road Racing Council.

Now the main opposition to massedstart racing comes from the N.C.U. andthe R.T.T.C., with a faint echo from thepresident of the R.R.A. who wronglyasserted that the movement was run by anumber of " hot-headed youths." Hesince has admitted that this statementwas wrong.Loose Ends

NOW let us draw together the loose ends.The N.C.U. is affiliated to the Union

Cycliste Internationale, which promotesmassed start racing on the Continent,and the N.C.U. issues licences to Britishriders to take part in those races. Why,therefore, is the N.C.U. opposed .tomassed start racing in this country(it claims, of course, that it is not)where the roads are no worse, and insome cases much better, than those, forexample, used in the our de France?And why is it that the R.T.T.C., whichwould not be in existence but for theattitude of the N.C.U. against road racing,now supports the N.C.U. ? A referenceto the -files of Bicycling News, whichwas the first cycling journal, willshow that the N.C.U. has made a muddleof nearly, everything which it has handled.In a leading article in that paper (September17th, 1895), the late John Urry, in givingadvice to clubs, wrote : " Above all thingseducate your members so that they may knowhow properly to express their feelings on theiniquitous conduct of the N.C.U."

It is humorous to think that the R.T.T.0and the R.R.A., both bodies which have beenformed as a result of a breakaway movement,should object to the formation -of theB.L.R.C. Now the time has come whenthe N.C.U. and the C.T.C. should droptheir pretence at representing cyclingopinion. Like the three tailors of TooleyStreet, an overlapping membership of

By F. J. C.

fewer than 50,000 cannot represent thev., million cyclists which it is presumedare on the roads. There is room andthe time is ripe for the formation of aCyclists' Association which is reallyrepresentative of the majority andwhich takes care to sound the opinionsof its members on particular subjects.It is humorous to think that the Cyclists'Touring Club, with its peculiar ideasof democratic principles, is so con-stituted that resolutions can be passedat its annual general meeting of whichno notice need be taken by its council.Affiliation

THE National Cyclists' Union acceptsaffiliation from cycling clubs which

exist only to promote time trials, andyet it is itself opposed to time trials.The contortions of this body -since itsfoundation are more reminiscent of aboneless wonder than of a cyclingorganisaticin.

In any case, as we have stated before,massed start racing in this country willcontinue in spite of the nonsense spoken bythe N.C.U. about amnesties and proclaimings,and all the other footling legal clap -trap withwhich it endeavours to surround its autocraticattitude.

Mr. Hepworth, M.P., was asked to have aword with Mr. Morrison on the Home Officeannouncement. Mr. Morrison replied toMr. Hepworth that the joint announce-ment " was purely a wartime measure."This statement contradicts that in the jointannouncement wherein it is implied that -massed start racing is undesirable in war,and that it will be more so in -peace. Thesponsors of the B.L.R.C. are in somewhatthe same position as the Tolpuddle martyrs.

As far as we can see there will be nosolution to this controversy unless theN.C.U. itself approaches the properlyconstituted new body concerned with aform of road sport outside the ambitand therefore the control of the N.C.U.New R.R.A. Records

ilOpECENT tandem tricycle rides by Messrs.-1- L. E. Copping and J. M. Sloper, ofthe North Road C.C., were passed asrecords : too miles in 4 hrs. 13 mins. 57 secs.;50 miles in 'hr. 52 mins. 41 secs.Take Care of Wartime Cycle TyresTHERE are over ten million cyclists in

' this country, which means that thereare over twenty million bicycle tyres inuse. That amounts to a great deal ofrubber so every cyclist must play his partin conserving this rubber to the utmost.

War grade tyres, of course, need extracare, and the best- way of servicing themis to keep them inflated hard. So pumpsshould be used regularly and often to ensurethat the share of the nation's preciousrubber supplies entrusted to cyclists is notwasted in any way.

26 THE CYCLIST

PARAGRAMS

'104,6000,14404t.i.,

.4 picturesque corner of the little South Doan village, Steyning, Sussex.

The, TrinityMRS. G. HARPER, Kingsbury Wheelers C.C., has

taken over the duties of hon. social secretaryfor her club. She is already hon. treasurer and hon.Time Trials stcretaO', two offices she took over fromher husband when he was called up.

. Dulwich Paragon in IndiaQTAFF SERGEANT LEN HANDS, Dulwich`-.1 Paragon, is now serving with the Royal Engineersin India.

LeaveWDDIE LAIDLER, Early Birds C.C., made most" of a short leave when he spent 54 days awheeltanderning in the Lake District. He has been servingon a submarine for many months.

Club RenamedCAMBORNE Redruth Premier C.C. has been ^

renamed the West Cornwall Wheelers. Reason :scattered.. membership. Cliff Hitchins, 23, KnaveGo -By, Camborne, Cornwall, is the hon. sec.

In Tanganyika'WORMER hon. secretary of the West Cornwall C.C.,

Denis Stuart is now in Tanganyika.

Pre-war Star's New RolePAT McCABE, Glasgow track star of pre-war days

is 'now in the.Merchant Navy.

Scottish Riders Meet AbroadWHILE with the R.A.T. in Calgary, Canada, " King

Ferguson, Glasgow Transport C.C., - met TomMcNulty, Glasgow Wheelers, leading road, track androller rider until he joined the R.A.F. three years ago.

Will Xeir's New ServiceASSOCIATION president and well-known Scottish

timekeeper, Will Keir, Dundee and Thistle RoadsC.C. and Dundee and District T.T.A., has gone to

,sea with the N.A.A.F.1.

George Owen's LossGEORGE OWEN, former English path champion

and brilliant Manchester Wheeler rider, lost hishome during a raid on- the south -ea t coast.

Manchester Wheeler's LossWORMER hon. gen. sec. of the Manchester Wheelers,

William Critchley died in a Japanese camp. Hewas in the R.A.F. and captured over two years ago.

News of Ealing MembersTWO members of the Ealing C.C.-Robert Butler

and Leslie Stokes-are prisoners of war imJapanese hands. Sergeant Syd Parker, R.R.A. tricyclerecord, holder, is with the Middle East Forces and hasmet Lieutenant D. Sargent, forrner club secretary.

Twice Captured, TIMMY PURVES, Veg. C. and A.C., long-distance

-0)1' J pre-war rider, is a prisoner of war in Germany.He was formerly captured in Syria but repatriatedafter cessation of hostilities.

Merseyside Wheelers Re-formTHE Merseyside Wheelers have re-formed and are

again in active operation despite the fact that20 members are in H.M. Forces.

Yorkshire Road Member's Promotion'K. V. HANCOCK, Yorkshire Road Club, has

been promoted to captain.

B. L. Smith's RecordRL. SMITH, Yorkshire Road Club, has a record

of which any rider might well be proud. Hecompeted in 22 titne -trials during 1943, won many club,semi -open and open events, and rode on the track andon rollers with success.

Portsmouth North End LossFOezo years a member of the Portsmouth North

End C.C., R. G. Foster has died. He was anardent tourist and had cycled in most of the Europeancountries.

The Barnsley WayTN six months during 1943 members of the Barnsley

C.C. won 24 first-class open events, x3 first team -race awards and 86 handicap awards. In 5942 the clubsecured no fewei. than 153 awards of all kinds.

D. Morrison Decorated -

TN. MORRISON, Glasgow Wheelers, now serving.2-. as a sergeant flight:engineer irt,the R.A.F., hasbeen decorated with the D.F.M.

January, 1944

From. Io,000 to 14 !BATTERY SERGEANT -MAJOR J. H. McLAREN,

Kings Lynn C.C., now serving in Egypt, rode54 miles during 1943 ! For many years his annualmileage was, th000.

Y.H.A. Reaches Ioo,000ARECORD total of too,no7, in Y.H.A. membership

was recently announced. London Region's shareof the figure is 27,840.

Track Racing in Oldham ?AT the recent zeneral meeting of the Oldham and

District Cyclists' Union a sub-c6mmittee wasappointed to look into the poSsibility of promoting trackracing in the Oldham district during the coming season.

Four Men in -a Weekrro lose four men for the Forces in one week is the

" record " of the A.E.C. C.C....The members areW. Hale, S. Page, K. Weeks and G. Hanger. The lastnamed was last year's club champion. '

Taylor AgainTACK TAYLOR has again won the West of Scotland

Clarion C. and A.C. championship.

Sergt. - Wall Missing -QERGEANT E. G. WALL, founder member of the`- Wings S. and S.C., is posted missing followingan operational.sortie over enemy -occupied country.

Club ChampionHJ. HUTSON. Bon Amis C.C., has won his club's

championship with an average speed of 22.166over distances of 25, so and too miles.

To Increase FundsVORKSHIRE Road Club has sent a suggestion toJ. the local R.T.T,C. Council that a penny levy bemade on every entry in open events. They estimatethat the Council could obtain k 200 a year by thismethod.

Escaped from CaptivityTVOR SANSUIVI, ace roadman of Swindon Wheelers,J was reported " missing " on his 'nth R.A.F.operational flight. That was five months ago. Hehas returned to this country and reports that in thecrash the pilot of the plane was killed and the rearygunner taken prisoner.

Oxford Rider's DecorationMEMBER of the Oxford City Road Club, Pilot Officer

Les King, R.A.F.V.R., has been awarded theD.F.C.

Sharrow Club Bereaved.TAMES WEAR, well-knon member of the ShimmyJ C.C., and prolific time-trialist for many years,died as the result of an accident when cycling.

Trool as Park !pLANS are afoot to make Glen Trool into a NationalJ. Park. Glen Trool has been described as thescenic gem of southern Scotland.

Against By-passST. ASAPH, the small North Wales city, is.objecting

to the line of a proposed new trunk road, and hassuggested analternative route.

Loch Long, and The' Cobbler (2,891 ft.).

January, 1944 THE CYCLIST 27

THE first annual dinner and dance andprize distribution of the West LondonRoad Club was held at the Park Royal

Hotel, Western Avenue, on November zoth.Over 15o people were present, and althoughthe club is only about a year old the attend-ance is an answer to those, especially theeffete members of the N.C.U., who stilldelude themselves into thinking they havekilled massed start racing. Mr. WilloughbyGarner, the president, was in the chair, withFrank Guy as toastmaster. Clubs repre-sented were Ealing Manor, Sandon, Southern.Coureur,, United Doom ers Calleva,Lawrence, Roslyn Ladies, Rickmansworth,Ealing, Leycrest Manor, and several others.

A few of those known to be hostile tomassed start racing sent excuses for their

'non-attendance. Mr. E. Mansfield proposedthe toast of the visitors, and Rex Coleyreplied. The toast of the Press was pro-posed byMr. W. S. Summers, and Mr. F. J.Camm, in his reply, dealt with the attitudeof the N.C.U. towards massed, start racing,and also with the attitudes of the R.T.T.C.and the R.R.A., which two 'latter bodieswere thetmelves formed as the result ofa breakaway movement and are thereforenot in a position to criticise the B.L.R.C.He poked fun at the use of the archaic legalterms " amnesty," and " proclaim " whichsuggested that the N.C.U. was a legal.authority.

He advised them to continue With massedstart racing, and stated that there wouldnot have been any Home Office announce-ment had it not been for the attitude ofthe N.C.U. and the R.T.T.C. He assuredthem that massed start racing would con-tinue. The evening was as historic as anevening in 1888 when the N.C.U. set itsface against road records and road 'acing-a stab in the back to cycle sport which noone in the cycling movement should heallowed to forget.

Sir Charles -Bressey at Roadfarers' CltibFRIDAY, November 12th, was an im-

portant occasion to the Roadfarers'Club when they held a dinner at the Waldorfwith Sir Charles Bressey as the speaker. Hissubject was his famous plan for Londonwith which he dealt in detail. He emphasisedand underlined the recommendation he madein his report, and received a great ovationat the conclusion, as well as a tribute fromthe president, Lord Biabazon.

Many famous members were presentincluding Mr. Sydney Camm (designer of

Around the WheeliworidBy ICARUS

the Hurricane, Typhoon, etc.), Mr. G. 0.Slade, K.C. (the famous counsel), Mr. C._ G.Grey, etc. The next meeting of the Road-farers' Club takes place on Friday, January21st, when Mr. H. G. Wells, a Fellow ofthe Roadfarers' Club and author of thefamous cycling novel " The Wheels ofChance," will be present,N.C.U. DiariesI HAVE received a copy of the first-class

N.C.U. diary which has been care -

The second and third prizes of five andthree guineas offered by the Tyre Manu-facturers' Conference have been divided -between them. Their fourth prize of oneguinea goes, to Mrs. I. 'W. Bogie, 10, GlebeGardens, Corstorphine, Edinburgh (" TyresLooked After Are Tyres Years After ").

There were 11;83o slogans sent in. Ifthis is the best slogan, the 11,829 othersmust' have been pretty foul. I can makeup better slogans than this all day long.For example :

Give tyres air,And save repair.

I do not think that Mr. Hogg's sloganwill become popular.

At the Roadfarers' Dinner, when Sir Chas. Bressey spoke on his Plan for London. Left to right :C. G. Grey, founder editor of The Aeroplane, Sydney Camm, C.B.E., F.R.Ae.S., designer ofthe Hawker machines, including the famous " Hurricane" and " Typhoon" (brother of the editorof this journal), Lord Brabazon of Tara (President), G. 0. Slade, K.C., the famous counsel,

and E. Coles Webb.fully prepared to include matter and dataof special interest to all cyclists. It alsoincludes 16 pages of maps. It_costs 3s. fromthe N.C.U., 35, Dotighty Street, London,W.C. t.

Airman Wins BicycleLEADII4G - AIRCRAFTNLAN R. C.

HOGG has won the bicycle offeredby the British Bicycle Manufacturers' Unionfor the best slogan on saving cycle tyres :" Use the rump and Save the Tyres."

Mr. W. C. Dowse, School House, Hedley-on-the-Hill, Northumberland(" Air and Care Save Wear and Tear "),and Miss Mary Watson, Westboarne Road,Lancaster (" A Pump a Day Keeps theTyres O.K.") have tied for second place.

C.T.C. Reward

THE C.T.C. offers a reward of los. toany person securing the conviction of

anyone depositing broken glass or any othersharp or dangerous substance on a road. Ioffer a similar reward to anyone securinga conviction of those caught stealing bicycles,lamps, pumps and other cycling impedi-menta! Of course, readers sending me thisinformation and securing these convictionswill be expected to spend their own timein the courts and pay their own expenses!

I notice at the -foot of the notepaper onwhich C.T.C. press notices are typewrittenthe following : " What do the cyclists say?If you want to know, ring up the C.T.C.News Department." I must ring up theC.T.C. News Department and ascertain howthey find out what the cyclists say. Shouldit not be what the C.T.C. Council says ?

At the Roadfarers' Dinner at the Waldorf on Friday, November tzth, 1943. Sir Chas. Bressey i> seen on Lord Brabacon'., right in rho righthand picture, and Sydney Cam on his left.

it

28

Sheepstor,Dartmoor village.

The User Critk SOME

of my friends having grown old with me...are now, in these travel stressed days, bemoaning

the fact that they have to " stay put " or incur theconsequences of discomfort attached to present-daytrain or bus travel. Now I feel scaly for those peoplefrom whom health has departed, or age prematurelywithered their activity, for there is no doubt such arefeeling increasingly the burdens of the limitations, andI wish they could be accommodated with private travelfacilities, even if only on a small scale. Perhaps theywill be in the near "future. But really I have littlepatience with the robust who will only give themselvesto cycling in the " five miles at a stretch " method,and then complain that cycling is hard work. Of courseit is if the individual will make no attempt to becomea cyclist, sits on the saddle like a sack of flour, doesn'tknow what gear he is pushing, and muffles himself upas if for an arctic exploration. Such people-and thereare Many-are no credit to the pastime ; they merelyderide it, and endeavour to reduce it to ridicule. Theyare not usually open to any kind of persuasion, andconsider themselves a cut above "paddling their owncanoe," which incidentally is surely the manly as well asthe healthiest method of travel. Now I have every desireto make the public cycle -minded, to propagate thisgrand game which I belieVe to be pre-eminent in thepleasure travel sphere, and will do anything reasonableto help people to enjoy cycling ; but I just have nouse for the type portrayed, the lazy people who want tobuy their leisure-which I interpret as sheer idleness-with the least possible' muscular energy. Cycling isnot for such as they; but one day when thickened

veins and pulsing heart overtakes them, they will besorry about it.

Spares anii CareTHE

industry is to -day very much alive to the needfor a much greater supply of replacements, and

recently approached the supply departments with aview to improving the position, particularly in referenceto pedals, spokes, bells, and inflators. How successfulthey will be remains to be seen. It is true that therepairer is wasting a lot of time these days searchingfor replacements, time that could be far more profitablyspent in servicing machines and quickly returning themto usefulness. The repair and replacement materialis simply not available in many 'cases, and thousands ofbicycles must -be immdbilized as a result, and thousandsmore are ridden to ruination for want of what used tobe a very simple replacement. It is a desperatebusiness.which the industry is trying its best to cure;but unfortunately many disappointed people areblaming the dealer and the trade for neglecting theirinterests. That such is not the case I can vouch for ;the trade is really worried over the lack of supplies,for it knows better than most people how much thebicycle counts in the transport system of the country.One thing you and I can and should do is to carefor our property, to oil and adjust it more assiduouslythan ever, because it is true that the main reason forbreakdown is the neglect of the simple attention abicycle needs. If these things were regularly attendedto, I believe a considerable percentage of the repair

to

THE CYCLIST '

problem would be solved, and thesaving in labour expense and worryWould be enormous. But howdifficult it is to bring this simplefact home to the average, rider; thatloose crank, that squeaking pedal,that maladjusted gear or slack bearing ;thex will all lead to trouble in duetime, and then the worry will start,whereas a few minutes' attention nowand then will cancel out half ourtransport troubles.

Go Out-Keep FitWINTER riding is so jolly. com-

fortable and companionable thatI sometimes wonder if it is not moreenjoyable than the summer solstice,when the very length of the daysoccasionally tempt us to long journeysand we are apt to arrive home atrifle weary. I say winter cycling iscomfortable because when 'darknessfalls I am generally within an hour ofhome on a/ratid I know well, so thatthe blackout seldom worries me:Ana. is companionable for the simplereason that most regularriders know thehaunts of their friends and can usuallyfind them ensconced by an ingle-nooktasting the tea or enjoying countryfare which is so often a change fromthe set round of rationed food. Forthe knowledgeable cyclist knows wherethe fat pig lives and usually discoversthe date of his demise-and actsaccordingly. At least I do. To stepinto a brisk air soon after breakfastand ride say fifteen miles to a well-known meeting place, puts you inform for a cup of tea and whatevermay be going in the -cake line ; andten miles farther there will be lunchwaiting for you at some cottage orhostel still in, fairly full working order,and a couple of merry talkative hoursflash by with little enough time left tomake a third call for tea on the, circuithome", leaving a bare ten miles to finisha day's easy riding. But how fit andsatisfied such a round keeps you, fillingyour eyes with the winter scene whichinvariably ends with a glorious sunset.Sometimes it is wet, yet even such

das have their charm and advgature, containing thatspirit of waywardness that is the very essence ofcycling. The man who "sticks in" because of theweather is surely admitting elemental defeat of thatfirst law of the animal, to go out and forage, Someday, when normality -in food' supplies returns. to theland, I will find me a merry companion and we willgo a long tour to the Western Highlands in mid -winter,and I know it will be good. I have wanted to do itfor years, but have always been afraid to pledge summer

January, 1944holidays to such a venture. Bin after the war is over,perhaps-indeed I hope-that the younger generationwill take the helm and grant me leave to widen mywanderings.

Good ReasonsT WAS talking to a relative of mine the other day

expounding the theory that my riding had resultedin the preservation of easy activity and the usual rudehealth I enjoy. This younger man happens to be adoctor with-in normal times-a wide practice, but atthe moment fulfilling duties in the army. Like mostmedical men the use of a car has become second natureto him, and' the only exercise he gets beyond runningup and down stairs is an occasional game of golf." Well," he said, " you may be right, but it would bea very unpopular thing for a medical man to recommendcycling as a cure for most of the ailments humanityis heir to. Certainly you are a decent specimen ofyour own belief, and it seems to me, fully justified insaying the deep breathing cycling engenders, and thesmooth exercise, of most of the muscles, have madeand keep you fit and well at sixty-four: But youmustn't expect me to become enamoured of such methodsto save humanity from its own folly. By all meanscarry on with the good work, for it is good work, andif finally we have to shoot you to end the story, don'tblame us, but your jolly old cycling habits." Thatidea is, of course, the licence of relationship ; but atleast it is something to get a frank opinion that cyclingis a fine thipg to practise, not merely for the youngsters,but for the growing elderly," who automatically thinka trifle more of theirhealth and the best way to preserveit. That I can work and walk and ride-particularlyride-gives -me great satisfaction in acquiring andpreierving the power to do these things; but all thatjoy is magnified amid the undiluted pleasure I obtainfrom looking on a fair countryside any cdd -hour,and trickling the round of friends when the deslre fora chat and exchange of opinion moves me.' ro think Iam free in my comings and goings ir fine, but to discover'in the processes of exercising such freedoms the depthof mental pleasure such changes reach, is just somethingthat cannot be transferred to words, it goes beyondexplanation:

A Thing to RememberAFTER this war is over I predict a great future for

the four -speed gear, either of the hub or derailleurtypes. I have been riding these combinations since 1939and have had every chance of comparing them with thetwo and three speed gears I still have in service. I saythis because I consider I am just an ordinary average'cyclist, and frankly admit when the four -speed becameavailable, did not realise it would be any great improve-ment on the previous combinations. Well, I waswrong, for it is, and the reason is chiefly due to- the

Vrange of ratios that seem to me to be just sufficient inchanging dimensions to give a wonderfully level useof all the gears over a give and take road, or under theconditions of windy and stormy weather, for or against.This matter is worth keeping in mind when the timecomes for you to order that superb new bicycle you havebeen talking about.

Club NotesTudhope WinsTACK TUDHOPE, Crawick Whs., won the ScottishJ Invitation " 25 " with a time of 1 hr. 4 mins.23 secs.

PromotionsTANLEY SADLER, well-known Newcastle club-

man, is now' a Captain in the R.A.S.C. in theMiddle East.

Douglas RollersTHE Douglas C.C. is promoting an open roller

contest on January 8th. '

Death of Wren PresidentFLIGHT -LIEUTENANT G. W. WARNES,

R.A.F.V.R., formerly president of the WrenWheelers, has died, in Johannesburg, South Africafollowing a long illness.

D.F.C. for Clubman .

TAILOT OFFICER BEN ROOKE. formerly -secretaryA and club champion of the Luton Arrow C.C.,has been decorated with the D.F.C.

" Twelves" AgainMO open " twelves " have been promoted in Scotland

since 1939, but riders are urging that they shouldbe revived in 1944.

Joined Yorkshire RoadsMR. AND MRS. ALF. MARTIN, South Yorkshire

speed stars, have joined the Yorkshire Road' Club.

In Air ArmRICHARD' CAMPBELL, son of John Campbell,AN championship secretary of the Scottish AmateurC.A., has joined the Fleet Air Arm.

Taylor WinsJACK TAYLOR, West of Scotland, has again won

the road championship of the National ClarionC. and A.C.

Tax DroppedTHE 5s. bicycle tax which the Nazis imposed on the

Dutch has been dropped.

Most Popular HostelTHE most popular youth hostel in Scotland during

1943 was -that at Edinburgh, with a total of 8,762visitors.

Cycling Chamberlain

GLASGOW'Snew City Chamberlain, Mr. George B.

Essletliont, is a keen cyclist.

No PumpsCYCLE inflators are reported to be so short that even

-the military cannot get supplies.

Clarion BrochurerrHE National Clarion C.C. is to issue a brochure to

A celebrate its jubilee this year.

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January, 1944 THE CYCLIST 29

CYCLORAMA

The Olde Ferric Inne, Symonds

Lindon Dairy FarmTHERE have 'been many books written

to emphasise the fact that rural lifeis still, io.-be enjoyed quite near to. London,and I have myself enjoyed the shooting ofhares on some farmland within the' sound,and almost sight, of a Tube station: Butit was only recently that I discovered that,right in London, there was a dairy farm,with some twelve milking cows, andauthentic, country -looking cow -sheds with,over each stall, the particular cow's nameinscribed; just as one may see it at DaisyDell Farm, in the heart of the countryside.Where- is it ? Why, in Swedenborg Square,Cable Street-which, as you may know, isin Dockland ! I have read all about it, andone fine day I have promised myself thatX. will visit this farm in the heart of theMetropolis, and see the " farmers "-Mr.and Mrs. Carson. and I shall take a keendelight in stroking the sleek neck of.Maudie "-one of the well -kept herd.

Children's Tricycles. judge from the " smalls in theadvertisements of various provincial

papers I have seen lately there is a greatdemand for children's tricycles, and I gatherthat big prices.are being paid by those luckyenough to find someone with a machine todispose of. It is all an interesting sidelighton the war, and. the acute shortage of certainthings. Who would have thought, in thepiping days of Peace, that when little Johnniewanted a child's tricycle, it would have beena matter of advertising and offering a " tip-top price " ?.

Keen Cyclist at 83TRULY, it is never too old to cycle . . .

and I was reminded of the fact quiterecently when I was visiting a Derbyshirevillage where the rector, a grand old fellow,is within a month or so of his eighty-thirdbirthday. And he proudly showed me a

astonishing comment"Yes, it is a goodbike ; I thought Iwould get a goodmachine that wouldlast ! " There spoke agreat - hearted than,and a true cyclist!

" Conkers " _ -

HOW some of theold and simple

games of Our boyhooddays survive and re-tain their freshness foreach generation ! Thisautumn I have spentmuch of my time in adistrict rich in finehorse --chestnut trees,and I could not helpbut notice bow popu-lar was the old game df" conkers "-a great

Yet .

favourite in my youngdays, and one which

is still played, apparently, according to, theold rules. And what a lot of pleasure ithas afforded generations of English school-boys! First, the gathering of the " conkers "-when 'the green sheaths have split, andthe shiny, tawny -nut emerges then, theboring of the hole through which to threadthe string or cord ; the tying of the bigknot at the end of the string . . . and thecocksure " challenge " to all and sundry!And-just ,as in the days of yore-the nutwhich smashes another becomes a "One-er "

. . and is treasured as the victories mountup. I love to see these survivals of a simplerage, and. I rejoice that the boys of 1943are not too sophisticated to enjoy thisvenerable game of the English town andcountryside.

Glories of DerbyshireJTALKED the other day with a man who

had just returned from a little cycletour in my beloved Derbyshire. He wentinto ecstasies over Dovedale, and Mill Dale,and all the lovely country around the Derby-shire -Staffordshire border . . . and he knewmy villages of Yeaveley, and Rodsley, andWyaston (where they "dress the wells atWhitsuntide)-and I told him of theDruidical Circle at Youlgreave, " and wechatted about the old " Green Min " atancient Ashbourne - that historic innwhere Doctor Johnson was wont to sit andsmoke and sip his ale. A great district, andif it is hilly . . . well, no true cyclist mindsa hill! When the war is over, and one cantake a real holiday, instead of snatching anodd day from the desk, I shall' ride againin Derbyshire where,the gentle Dove windslike a silver ribbon through matchless scenicsplendour, reminding one of Izaak Waltonand Charles Cotton, and happy hours withrod and line.'Winter Beauty

ARAW, cold, rather. dismal Decemberafternoon

' and as I write these notes

Mother Nature does not seem to have much

new bicycle which,after much trouble, hehad secured from adealer in the neigh-bouring marke t -town. The old manshowed me his newacquisition with apardonable pride, andmade the-to me- Farmer Hodge 's young stock and smell the

good aroma of the farmyard, and maybehave a word with him about his BlackLeghorn pullets which should now becoming into lay. And Rufus-that's the

- liver spaniel with the limpid eye and faithfulheart, wants a run and a blow, anyway.And once outside, what I might havemissed! After that shower of rain . . . arainbow, wondrous and glorious, pledge ofall the sunshine to come to gladden heartsand earth. . .

By

H. W. HEY'-to offer me should I tramp out along mywell -loved lane, which leads to Three ElmsFarm. And yet . : . there is beauty in thosestark trees ; blackbirds hop , out from theshrubs along the edge of the sodden lawn,and a robin has been hopping about hope-fully for some time around the bed ofchrysanthemums. I think I will go out,and, anyway, it will be good to look at

"Robin Hood " Cycles

CHATTING with my good friend Keller,''of the Raleigh Company, I gathered

tliat the " Robin Hood " range of cycles has"gone over" well, and that everyone isvery satisfied. The ." Robin Hood " nowsupersede,s the Gazelle," and the appropri-ateness of the new name is now evident.

Care of Tyres !CONTINUE to take great care of your

tyres! The very optimistic commentscne reads and hears about the developMentof synthetic rubber are apt to be mislead-ing ; the real experts, the men who know,say that our rubber problem is by no meanssolved, and that every user of tyres musttry to get the last mile out Of them and'treat them very carefully. So . . . let uscontinue to " do our bit " in this direction!

Cycle InflatorsHAVE heard much lately_ about the

J shortage of cycle inflators, and morethan one cyclist has pointed out that theurgent advice to riders to "keep their tyreshard" is difficult to follow when one cannotbuy a pump. Well, there is a shortage, butthen there are shortages of many things inthese wartime days, and I suppose we mustnot grumble. It can be stated with confi-dence that manufacturerS, and that hard-working body, Tyre Control, are doing allthat is possible to improve the position, butwhile the shortage lasts it is no bad planto do as one tyre manufacturer is advocating

. . " Share your pump with, a pal."

Post-war DemandsTHE recent good news front several war

fronts is reflected in the optimistic notewhich is apparent in much advertisingto -day ; there is a "looking forward " tothe better times of Peace, which is refreshing,and although 'one does not make anyprophecy about the " end of the war," onedoes feel that it is right and wise to impressupon dealers the fact that good times arecoming, when demands will be big, andBritish craftsmanship will be equal to thosedemands. In the world of cycles, I am surethat we shall find that even during thesehard days of war our technical leaders havebeen busy " evolving "-and they will givethe dealer all that he wishes in the way ofdesign and quality when the great daycomes.

4

30

F

THE CYCLIST January, 1944

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THE, CYCLIST 31January, 1944

We?:;f..'" Artr-.;Z:la/1.0' VAIW.01QM4

The Pastime's EnemiesCYCLING has a number of climatic enemies, which

take their turn at heading the unpopularity poll.I, persoitally, do not reckon extreme heat or extremecold anion; those foes, though certain cyclists arealways ready to make use of either excuse for keepingoff the read. In the -presence of severe ups and downsof weather the great thing is to dress for the part, andyou won't take any harm. No; the enemies I have inmind are heavy head -winds (especially one with a lotof east in it), snow, glazed frost and fog. A coldopposing breeze is not a nice conipanion on a long ridein winter, though it can be neutralised. Deep snowis a real" buffer -stop." Glazed frost --a rare enoughoccurrence, thanks be !-renders the maintenance ofan upright position' very difficult, and generally putspaid to cycling. Fog has a demoralising, but notexactly .,a demobilising, effect on one's wheelingactivities.

There came a Saturday towards the end of Novemberwhen, had I known what was in store for me, I might-I said might "--have been tempted to stay athome. During the afternoon the temperature fell.It bit my bare knees, as well as my fingers and toes,and, in the evening, I ran into one of the thickest fogsever. Down went my pace, and, as usual in suchcircumstances, it was impossible to ride fast enoughto keep warm. So now and again I dismounted and"danced " my' way along the road. I subsequentlysympathised with a lorry -driver who was using aone-way road in the wrong direction, as well as witha van -man who had invaded the side-walk-because.on no fewer than three occasions I found myself at theextreme right-hand side of the highway I Three times,also, I was completely lost-on roads f know as wellas the palm of my hand. Early on in this thickness1 had tried carrying my lamp on the front fork. but thebracket, unfortunately, is fitted on the right-hand side-in other words, on the wrong side-and all Iobtained for my enterprise was the perplexing shadowof the wheel, which was a distinct hindrance to theprocess of,keeping my eye .on the grass verge. Having

irequired, n these difficult conditions, 21 hours to travela mere 17 miles, I have no hesitation, at the moment,in characterising fog as' cycling's No. r enemy !

Forbidding DayAFTER such a clammy experience as this, one might

have expected that I would be content to " liedoggo " on the following day. But no we cyclists-.or some of us-are not like that ; at any rate, we arenot so easily beaten. That Sunday was one of the mostforbidding days in my experience. At first it was notraining, but it was a passable imitation. The air wasfull of moisture, the trees were dripping, and visibilitywas next-door to nil. Realising that there may comedays when the pastime's climatic enemies will keep meat home, I decided to sally forth, in accordance withplan-and right glad I was afterwards. A roundaboutride of 25 miles, mostly inside my cape (for the moistnessturned into actual rain), brought me to a well-earneddinner and a roaring fire, plus some pleasant cyclingcompany (for one or two other hardy souls were abroadon that forbidding day), and a journey of a further 23miles carried me home in time for tea, feeling more thancontent. Having changed my moist shoes and stockings,I thoroughly enjoyed a quiet evening by the fire, withthe memory of "something -attempted, somethingdone" in uninviting conditions.

Hill ThrillsNOW let's talk about something wanner! One hot

afternoon in the late summer I was just aboutready for whatthe French call " the five o'clock." Nearlyat my proposed destination, I discovered a tandemcouple, heavily laden as to both selves and steed,who were obviously, looking round for an establishmentin which to refresh themselves. Inquiry confirmedmy suspicion, whereupon' I,said that, if they cared toride along the road with me for a mile or so, I wouldsee them right. So we had a pleasant meal in the

My Pointof ViewbY WAY PARER®

, Agarden of a tea -house familiar to me, whilstwe discussed the Welsh tour upon which

'the ypung couple were just embarking.Afterwards my photograph was taken-

' why, heaven only knows I-and then I putmy new friends back on their road, andforgot all about them. But a month latera snap " arrived, together with a nicechatty letter from the young man. Theyhad enjoyed their 600-anile tour, andhis wife had been thrilled at seeing

The Door of EnglandDERHAPS I am biased because of a short residencex in the town during the last great war, but I havealways regarded Dover as a most depressing place.Regarded as a seaside resort it is a dismal failure, as thegreat stone arms of the harbour not only seem to claspthe whole of Dover within their jealous embrace butthey also prevent any wide view of the open sea. Inspite of this Dover is a most interesting and romantictown. It has been known as the " key to England " formany centuries, and perhaps an even more apt titlewould be the -" gateway to England." Here at any ratemost of the continental traffic enters or leaves ; herealso is the south-eastern end of one of the, country'sgreatest highways, the_Watling Street, that served --the .country for some zoomiles. There is plenty tointerest the tourist and notthe least impressive featureis the great old castle stand-ing on the cliffs as if defyinginvasion. Its story goesback to times before theRoman invasion and it isobvious that it has beenadded to and strengthenedin later centuries. Muchof the earlier work wasdestroyed in comparativelyrecent times; when it wasfeared that Napoleonintended to pay us a visit ingreat strength.

Gateway to DartmoorDOVER is not the only

place to which onecan apply the word" gateway,':- and I oftenthink that Moretonhamp-stead in Devon isthe real gateway toDartmoor. 'Fhe moor hasreally few approaches, sothat any town onsits fringecan be so regarded. Moreton

mountains for the first time in her life..Si Ivtaty the Vilaln. Agider61.1(0.'-)

Stret-orK. The word "thrill" is liable to be over-worked (like " definitely "), but I believe it

to be correctly used to describe some of the delightswhich cycling bestows_ upon us. It is a thrill todraw mountains into one's sight-especially, perhaps,for the first time. It 'is a thrill to cycle throughthe Vale of Llangollen, whether for the first,. or thethrst time, as it is an eternal thrill to loiter atCapel Cling and look along the Gwryd Valley toSnowdon. It is a thrill to see the Langdale Pikeslift into the picture, or to spot Ben Nevis, or BenCruachan, or Schiehallion. It is no less a thrillto ,draw towards one -of the mountains comprisingKillarney, on the approach from Mallow, or to seeConnemara's mighty uplift from the south side ofGalway Bay. And thrill is the word for it when,somewhere on the northern coast of. Ireland, youbecome conscious that the dim etching on the sky -lineis Scotland,, or when, on the west coast -of " the Lando' Cakes;" the sprawl of the Outer Hebrides entersthe, picture.

SO I am not at all surprised that the young womancyclist, whom I met in the heart -of England, wasthrilled when the great earth masses of the Principalitycame into her life, in the course of a cycling tour.And there, I think, they will remain for many a day,to provide a precious memory of " things seen."

Prized LuggageT RECEIVED a letter the other day from a very

special touring companion, whose active associationwith me along the road was fractured some years agoby his departure abroad, first to Paris,. then to Prague,then on a sort of roving commission between Icelandand the Canary Islands, and afterwards to Bombay,whence he passed on to Calcutta, where he is nowlocated. The point in his letter which is of specialinterest to us in this place is that my friend has takenwith him, as prized luggage throughout his extensivetravels, a number of half -inch cycling maps. ' One canimagine the joy which accrues to him by virtue ofperusal Of these pictures of now far -distant country,and the manner in which he is able to transport himselfin thought to those areas where he and I used to frolicin days gone by-Cheshire and Shropshire, the NewForest and Devon, Wales and Ireland. With hisvivid imagination and excellent memory, he will beable to " fight his battles o'er again," and I am surethat he is able to extract from his prized luggage a fairmeasure of the old delights which came to him throughparticipation in cycle touring. The pleasure he thusenjoys is for us as well, through the medium of ourmaps. But active cycling is a condition, precedentthereto.

C. Fox Hon. Sec. of the British League ofRacing Cyclists.

Notes of a HighwaymanBy LEONARD ELLIS

always seems to be a delightful place in which to staya night. Although tiny and with not many attractions,there are some good hotels, and what is more, Dartmooris within a hop, skip and a jump on the followingmorning. No tourist, however, will go away withoutseeing the very fine row of almshouses in the mainstreet, in fact he will be quite unable to miss them, theyconstitute the most attractive feature of the whole town.They. seem oddly out of place in this quiet town withtheir rounel-arched, arcaded front, but few will want topass without taking a photograph. Nearby is the remainsof the old village cross and one may also find thesuccessor to an old elm that was known as theDancing Tree-it is supposed a sort of natural villagemaypole.

The Abitshouses, Moretonhampstcad.

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MORSE KEYSNaCti9. On A reuillat ion size Tapping Key. Ourheavy brass model Is Atounterl ou a wooden base;has an adjustable gap and nickel contacts. Key ismired to work buzzer or flash lamp by using a 31 -voltbattery or the transformer descrilied above.BRASS KEY. 68, Chromium plated, 7/8. W.O.Model with heavy 'brass bar and the addition of afront bracket, 9/8. C.4roullum plated, 10/6. The above keys are supplied to the Services for MorseMatt action. Slightly snarler Key, 4/8. Junior 1fey,mounted on a bakelite base together with a Maxey5/... Should you reunite a coMplete outfit, our D.X.2Set misists of a heavy key, mounted on a largepolished hoard, 10in. x together with a Miner,flash lamp, bulb and holder with two switches tobring either into circuit. Terminals are also providedfor distant sending and receiving. 191. pos,- 8d.

MICROPHONESJust the thing for impromptuvoneerts, room to moot com-munication. ele. Bakelite. tablemodel, 8/9 8uspensinn type asshown, 8;6: Post 63. SuperModel on stand. 12/-. Fittinglust ructions included. Mike but-tons, 28. Tranuformen,

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-No. 3 _HEAVY DUTY doublecoil, 9¢9, poet 3d:

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WATT WIRE END Resistances, newand sussed, assorted sizes (our .assort -mom T, 5/6 per doz. : post free.SOLID BRASS LAMPS (wing type), one -hole mounting, fitted double contactsmall B.C. holder and 12 -volt 16 wattbulb. 3/6 each, post free, or 30,'- per doz.,earrMge paid.TUNGSTEN* CONTACTS, 31min. dia., a

lair mounted on spring blades, also twohigh quality pure silver contacts S/utin.,IM., also mounted on spring blades fit forheavy duty, new anti unused ; there isencnth base to remove for other work.Price the set of lair contacts, 5/- post free.AUTO TRANSFORMER. Rating 2,000

, watts, tapped ii -110-200-220-240 volts,. as new. Price £9, carriage paid. '

RESISTANCE MATS, size Bin. by 6in.,'set of four, 80-80-150 and 61)0 ohms, tocarry} to amp. Price, set of four, 5/-,post free.,atovirta COIL Ampmeter, dia.,panel mounting, reading 0.20 amps.,F.S.D. 15 in/A. Price 30/-, post free.'MOTOR DRIVEN PUMP, 100v. D.C.motor, " Keith Blackmail," k H.P. ;Inlet and outlet, gear type pump, in

-- 'ffect working order. Price £5, carriageti: Ditto 220v. D.C. motor, gin. inlet

and outlet. Price 57/0/0, carriage paid.'ROTARY CONVERTOR, D.C. to AA:.Input 22 volts D.C. (twenty-two). Output500 volts. at 140 rn/A, 50 cycle, singlephase, ball bearing, in first-class eon.dition, no smoothing. Price carriage paid.£3.1111-CLIAISFMETER, flush nitamting, 2iin.did:, range 0400 ana/A', shunted, movingcoil. Price, £2. post flee.MOVING COIL AMPMETER, 21in. dip.,range 04 amp., panel mounting, F.B.D.15 in/A. Price 257-., post free.MASSIVE GUNMETAL WINCH, completevith long. handle, for use with VII. wirecable,. weight 50 lbs., condition as new.Price £3, carriage paid.RECORDING AMPMETER in large iron-

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SUPER SENSITIVE RELAYS, multi -leaf,P.O. type, very low rn/A working, condi-tion new. Price 15/-, post free.ROTARY. CONVERTOR, D.C. to D.C.Input 24 volts, output 1,000y. at 250 nt/A,D.C. choke and condenser smoothingfitted to both input and output, conditionas new, weight 85 lbs. Price £10, carriage

METER MOVEMENTS, moving coil, forrecalibratiom laggeSize, 4 to 6 in. full-scale deflections, average deflection 30 m/A.Price 15/-, post free.AUTO TRANSFORMER, 1 kW., tapped0-110-200-220-240, step-up or step-down,condition as new: Price £5, carriage paid.RESISTANCE UNITS, fireproof, size 10in.by lin., wound chrome nickel wire,resistance 2 ohms to carry 10 amps.Price 2/6, post free.:EPOCH SPEAKER, super cinema Model,20 watts output, 15 in. cone, 15 ohm coil,6 -volt field. no ener,qising. Price £7/107-,carriage paid.DYNAMO, shunt. wound, output 5p. volts6 amps., -speed rig oilerbearings, in &tot -class condition.. PriceSS, carr. paid.D. C. MOTORS, 110v volt series wound,approx. 1/10 11.P., ball, bearing, totallyenclosed. Price 12'6, carr. paid.

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Revealing every detail with startling exactness,highly magnified and brilliantly illuminatedin natural colourings, it presents in manyinstances hitherto unsuspected data whichcan be used to advantage.

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