JOURNALOF THE

FRANKLIN INST TUTF OF T H E STATE OF PENNSYLVANIA

FOR T H E P R O M O T I O N O F THE MECHANIC A R T S

VOL. CLXI, No. 5 8IST YEAR MAY, 19o6

T h e Franklin Inst i tute i s not respons ib le for t h e statementsand opin ions advanced by contributors to t h e Journal

T H E F R A N K L I N I N S T I T U T E .

Franklin as a M a n of Science and an Inventor.*[An address delivered by Dr. E d w i n J. Houston, Emeri tus Professor of

Physics, Frankl in Institute, o n February 21, 19o6, on the occasion of the 2oothanniversary of the b i r th of Benjamin Franklin.]

(Concluded from voL clxL 2" 3 I6)

"Fig. ii is to represent the elevation of a water-spout, wherein, I sup-pose P P P to be the cone, at f irs t a vacuum, till W W, the r is ing coiumnof water , has filled so much of it. S S S S, the spiral whirl of air sur-rounding the vacuum, and continued higher in a close column after thevacuum ends in the point P, till i t reaches the cool region of the air. B B,the bush described by Stuart, surrounding the foot of the column of water.

(h) "Now, I suppose this whirl of air will,at first, be as invisible as the airitself, though reaching, in reality, from the water, to the region of cold air,in which our low summer thunder-clouds commonly float; but presently, itwill become visible at its extremities. A t its lower end, by the agitation ofthe water under the whir l ing part of the circle, between P and S, forming Stu-ar t ' s bush, and by the swelling and r is ing of the water , in the beginning vacu-

*Copyrighted by Edwin J. Houston, 19o6. 'VoL. CLXI, No. 965 2 1

3 2 2 2r-Zoltstolz ." [J. F. I.,

S m ~

B

Fig. 11. E levat ion of W a t e r Spout .(Franklin)

urn, which is, at first, a small, low, broad cone,whose top gradually rises and sharpens, asthe force of the whirl increases. At itsupper end it becomes visible, by the warmair brought up to the cooler region, whereits mois ture begins to be condensed intothick vapour, by the cold, and is seenfirst at A, the highest part, which beingnow cooled, condenses what rises next atB, which condenses that at C, and thatcondenses what is r is ing at D, the cold op-e ra t i ng by the contact of the vapors fasterin a r igh t line downwards, than the va-pours themselves can climb in a spiral lineupwards; they climb, however, and as bycontinual addition they grow denser , and,concentrating currents that compose thewhirl , they fly off, spread, and form a cloud.

"It seems easy to conceive, how, ~oythis successive condensation from above,the spout appears t o drop o r descend fromthe cloud, though the materials of which itis composed are all the while ascending.

"The condensation of the moisturecontained in so great a quant i ty of warmair as may be supposed to rise in a shor ttime in this prodigiously rapid whirl, is,perhaps, sufficient to form a great extentof cloud, though the spout should be overland, as those at Hatiield; and if the landhappens not to be very dusty, perhaps thelower par t of the spout will scarce becomevisible at all; though the upper, o r what iscommonly called, the descending part, bevery distinctly seen.

"The same may happen at sea, in casethe whirl is not violent enough to makea high vacuum, and raise the column, &c.In such case, the upper part A B C D onlywill be visible, and the bush, perhaps,below.

"But if the whirl be strong, and therebe much dust on the land, and the col-

May, 19o6.] Frauklin as aMalz of Scienec and an I~wentor. 323

unto W W be raised from the water, then the lower part becomesvisible, and sometimes even united to the upper part. For the dust may becarried up in the spiral whirl, till it reach the region where the vapour iscondensed, and rise with that even to the clouds: And the friction of thewhirling air, on the sides of the column W W, may detach great quantitiesof its water, break it into drops, and carry them up in the spirial whirlmixed with the air; the heavier drops may, indeed, fly off, and fall, in ashower, round the spout; but much of it will ,be broken into vapour, yetvisible; and thus, in both cases, by dust at land, and, by water at sea, thewhole tube may be darkened and rendered visible.

"As the whirl weakens, the tube may (in appearance) separate in themiddle; the column of water subsiding, and the superior condensed partdrawing up the cloud. Yet still the tube, or whirl of air, may remain en-tire, the middle only becoming invisible, as not containing visible matter."

(a) Here we have the ring of the true philosopher: "Nothing,certainly, can be more improving to a searcher into nature thanobjections, judiciously made, to his opinion, t a k e n up, perhaps ,too hastily." Franklin welcomes the fair criticisms of theBoston Doctor.

(b) " I am so engaged in business, public and private." To allwho are acquainted with the immense amount of work perform-ed by Franklin, it is no t surprising that he finds but compara-tively little time for the more pleasing investigations of science,But it was then , as it is now, that it is the busiest man who finds-.time for all necessary w o r k , and F r a n k l i n certainly found time.in this case to prepare the most excellent scientific paper he-sent to the Boston Doctor.

(c) Even if the vacuum were complete, the height of the col-umn that is pressed inwards by the weight of the atmosphere~could not. greatly exceed thirty feet . ~:

(d) " I must , however, no longer call it my hypothesis ." Agenerous statement , s ince Stuart 's explanation was certainlyvery obscure.

(e) F r a n k l i n is quite correct in this supposition. Thewhirlwindand the waterspout are the same phenomena, being due to thesame causes, with, however, the difference that the whirlwind isproduced by a whirling c o l u m n of air pass ing over the land,while the waterspout is produced by this c o l u m n pass ing overthe water. Note here the clear and logical statement as totheir resemblances.

324 Z-tous lon : [J. F. I.,

(I) Both waterspouts and whirlwinds possess a progressiveas well as a ro ta ry or circular motion.

(2) Both waterspouts and whirlwinds occur after periods ofgreat atmospheric heat, when the air has been free from winds.

(3) The wind blows in all directions from the extended spacesurrounding both water-spouts and whirlwinds directly towardsthe water-spout or the whirlwind.

(4) When waterspouts, by reason of the i r progressive mo-tion, leave the sea and move over the land, they produce all thecharacteristic effects of whirlwinds, thus showing them to bethe same.

(5) /3cth waterspouts and whirlwinds occur most com-monly during the day time.

(f) Franklin now proceeds to apply his theory as regards theformation of waterspouts, producing for this purpose a plan andan elevation of the spout as he conceives it to be produced. HeLases his theory on two assumptions, that all should be willingto admi t ; i . e . , - -

(i) A higher temperature in the lower regions of the atmos-phere than in the upper regions, and, consequently, a morerarefied condition near the surface of the earth than in the up-per regions. Such a condition would, of course, necessitate anabsence of wind.

(2) An exceedingly moist condition of the atmosphere.Franklin then draws a picture of an extended area of land or

sea, of, as he says, perhaps sixty miles square. Ur~der condi-tions of prolonged calm, and with no clouds in the sky to pre-vent the sun's heat from freely reaching the earth's surface,these conditions perhaps continuing for several days, the lowerstrata of air become intensely heated. He then pictures thesurrounding air as being relatively much colder, and as, there-fore, remaining much heavier than that over the heated area.Under these circumstances, there would necessarily be produc-ed a rising or ascending current of the lower air, accompaniedby the descent of the colder and heavier air. But this risingdoes not immediately take place alike over all portions of theheated area. It begins over that portion of the area which is

May, 19o6.] Franklin as aMan of Scienec and an Inventor. 325

the m o s t h i g h l y h e a t e d , the r e m a i n i n g p o r t i o n of the w a r m airf l o w i n g horizontally over all por t ions of the h e a t e d a r e at o w a r d s this c o l u m n . In this w a y , the w h i r l is f o r m e d p r e t t ym u c h as F r a n k l i n r e m a r k s , like the funnel-shaped d e p r e s s i o np r o d u c e d in the s u r f a c e of the w a t e r in a tub, that is d i s c h a r g i n gi t s w a t e r t h r o u g h a hole or o p e n i n g in the b o t t o m of the tub.

F r a n k l i n then p o i n t s ou t the fact that s i n c e i n f l o w i n g h o r i -z o n t a l c u r r e n t s p o s s e s s c o n s i d e r a b l e m o t i o n , w h e n they r e a c hthe c e n t r a l r i s i n g c o l u m n , they are u n a b l e t o s u d d e n l y c h a n g et h e i r d i r e c t i o n t o that of the vertical m o t i o n , so that they jointhe a s c e n d i n g c o l u m n by m e a n s of a s p i r a l m o t i o n .

F r a n k l i n then p o i n t s ou t the fact that the veloci ty of theinflowing c u r r e n t will necessarily be g r e a t e s t in t h o s e por t ionsw h e r e the t e m p e r a t u r e of the air is g r e a t e s t ; i. e., n e a r t h ehighly-heated s u r f a c e . C o n s e q u e n t l y , it is here that the w h i r l -in~ m o t i o n is the swiftest, a n d , therefore, the v a c u u m m u s t beg r e a t e s t near the e a r t h ' s s u r f a c e , d e c r e a s i n g as the c o l u m nr i s e s .

(g) F ig . IO is clear, and n e e d s no explanation. The r i s i n g ofthe w a t e r from the s u r f a c e of the sea is a n a t u r a l r e s u l t of thep a s s a g e of the v a c u o u s a r e a .

(h) T h e w h i r l i n g m o t i o n of the air is at f i r s t invisible, butf o r m s a m a s s of c l o u d s as soon as the m o i s t air is c o n d e n s e d bythe c o l d . It is for this r e a s o n that the s p o u t may s e e m t o dropor d e s c e n d from the c l o u d s , a l t h o u g h the m o i s t u r e of w h i c h it isf o r m e d has been continually a s c e n d i n g .

I n a d d i t i o n t o the v a l u a b l e p a p e r s p r e p a r e d by F r a n k l i n ong e o g r a p h i c a l p h y s i c s , t o w h i c h we have a l r e a d y r e f e r r e d ; i. e.,the p a p e r as t o the c a u s e of t h u n d e r - s t o r m s , the a u r o r a b o r e a l i sand w a t e r s p o u t s , t h e r e yet r e m a i n s t o be d i s c u s s e d an o b s e r -v a t i o n of very g r e a t v a l u e r e s p e c t i n g the c a u s e of the g r e a tn o r t h e a s t s t o r m s of the U n i t e d S t a t e s . S i n c e , as is now wellk n o w n , the g r e a t e r part of the w o r k of the U n i t e d S t a t e sW e a t h e r B u r e a u as r e g a r d s the p r e p a r a t i o n of forecasts ofc o m i n g c h a n g e s in the w e a t h e r , is b a s e d on the peculiarities ofthe m o v e m e n t s of o u r g r e a t n o r t h e a s t s t o r m s , it will r e a d i l y beseen that this d i s c o v e r y of F r a n k l i n ' s s h o u l d be r a n k e d a m o n gthe m o s t i m p o r t a n t of his r e s e a r c h e s in g e o g r a p h i c a l p h y s i c s .W h i l e from a p o p u l a r standpoint , this m a t t e r is not so a t t r ac t -

326 ]-]ouston : [J. F. I.,

ive as his d e m o n s t r a t i o n of the ident i ty of d i s r u p t i v e electricd i s c h a r g e s a n d l i g h t n i n g , yet from a scientific standpoint , its h o u l d c o n t r i b u t e t o his m e r i t e d r e p u t a t i o n as a philosopher,as m u c h , if n o t m o r e , that his f a m o u s k i t e experiment . T h e n ,too , from a p r a c t i c a l s tandpoint , w h i l e it m i g h t s e e m that theinvention of the l i g h t n i n g rod was o.f m o r e d i r e c t b e n e f i t tom a n k i n d , yet the s a v i n g of life and p r o p e r t y that w o u l d fre-q u e n t l y r e s u l t from the t i m e l y w a r n i n g of the a p p r o a c h of ad a n g e r o u s n o r t h e a s t s t o r m w o u l d p r o b a b l y be i m m e n s e l yg r e a t e r than w o u l d ever be p o s s i b l e by p r o t e c t i o n a f f o r d e d byl i g h t n i n g r o d s .

F r a n k l i n i n f o r m s us j u s t how h e c a m e t o t h i n k of the c a u s e sof the g r e a t n o r t h e a s t s t o r m s in this c o u n t r y as s t a r t i n g in ana r e a of low b a r o m e t e r s o m e w h e r e in the wes t and p r o g r e s s i n gg e n e r a l l y t o w a r d s the nor theas t . I t a p p e a r s that a n e c l i p s e ofthe m o o n was t o be v i s i b l e at P h i l a d e l p h i a o n a c e r t a i n F r i d a yat 9 P . M . F r a n k l i n made p r e p a r a t i o n for the p r o p e r o b s e r v -ing of this eclipse, but, unfortunately, that n i g h t a s t o r m visitedPhiladelphia, a p p r o a c h i n g the c i ty from the nor theas t , a n d con-t i n u i n g violently all that n i g h t and the n e x t day, p r e v e n t e d anyo b s e r v a t i o n s of the e c l i p s e from b e i n g m a d e . T o F r a n k l i n ' sg r e a t astonishment, the n e w s p a p e r s c o n t a i n e d a n a c c o u n t ofthe fact that this eclipse h a d b e e n o b s e r v e d in the c i ty of B o s -ton . S i n c e this s t o r m a p p a r e n t l y a p p r o a c h e d the c i ty of P h i l a -d e l p h i a from the nor theas t , it w o u l d s e e m that it s h o u l d haver e a c h e d B o s t o n b e f o r e it r e a c h e d Philadelphia, B o s t o n b e i n g ,as is well k n o w n , n o r t h e a s t of the c i ty of Philadelphia. W r i t -ing t o his b r o t h e r , w h o l i v e d in the c i ty of B o s t o n , he a s c e r -t a i n e d the fact that the e c l i p s e was over a t l e a s t o n e h o u r b e f o r ethe s t o r m c o m m e n c e d . This c a u s e d F r a n k l i n t o m a k e f u r t h e ri n q u i r i e s , w h e n h e f o u n d t h a t , as a r u l e , the g r e a t n o r t h e a s ts t o r m s of this c o u n t r y b e g i n t o the l e e w a r d ; i. e.., s t a r t s o m e -w h e r e t o the s o u t h w e s t , then m o v i n g in a g e n e r a l n o r t h e a s tp a t h a c r o s s the c o u n t r y .

In a l e t t e r t o the Rev. J a r e d El io t , d a t e d Philadelphia, JulyI6, I747, F r a n k l i n s a y s :

"We have freqently, along this Nor th American coast, storms from thenortheast, which blow violently sometimes three or four days. Of these Ihave had a very singular opinion some years, viz., that, though the course

May, 19o6.] Franklin as aMan of Scienec and an Inventor. 3 2 7

of the wind is from northeast to southwest, yet the course of the s t o r m isfrom southwest to northeast; t h a t is, the air is in violent m o t i o n in Vir-ginia before it moves in Connecticut, and in Connecticut before it moves atCape Sable, &c. My reasons for this opinion, (if the like have not occurredto you,) I will give in my next."

I n a n o t h e r l e t t e r t o t h e s a m e g e n t l e m a n , d a t e d P h i l a d e l -p h i a , F e b r u a r y 13 , 1 7 4 9 - 5 o ( y e a r u n c e r t a i n ) , he fulfil ls t h ep r o m i s e r e f e r r e d t o in t h e p r e c e d i n g l e t t e r , and at f a i r l y fulll e n g t h r e g a r d i n g his v i e w s o f t h e m o t i o n o f t h e n o r t h e a s ts t o r m s :

"You desire to know my thoughts about the northeast s tq rms begin-ning to leeward. Some years since, t h e r e was an eclipse of the moon atnine o'clock in the evening, which I intended to observe: but before nimhta s t o r m blew up at the northeast, and continued violent all n igh t and allnext day; the sky thick-clouded, dark and rainy, so that neither moon nors t a r s could be seen. The s t o r m did a great deal of damage all a long thecoast, for we had accounts of it in the newspapers from Boston, Newport,New York , Maryland, andVirginia; but what surprisedme was, to find in theBoston newspapers an account of an observation of that eclipse made the re ;for I thought, as the s t o r m came from the northeast, i t must have b e g u nsooner a tBos ton than with us, and consequently have prevented such obser-vation. I w r o t e to m y bro the r about it, and he informed me, that theeclipse was over t h e r e an hour 'before the s t o r m began. Since which I l~avemade inquiries from time to time of travellers, and of my correspondentsnortheastward and southwestward, and observed the accounts in the news-papers from New England, New York , Maryland,Virginia, and South Caro-lina; and I find it t o be a constant fact, that nor theas t s t o r m s begin to lee-ward; and are often more violent t h e r e than farther to windward. Thus thelast October storm, which with you was on the 8th, began on the 7th inVirginia and N o r t h Carolina, and was most violent there.

"As to the reason of this , I can only give you my conjectures. Supposea great t r ac t of country, land and sea, t o wit, Florida and the Bay ofMexico, t o have clear weather for several days, and to be heated by thesun, and its air thereby exceedingly rarefied. Suppose the country north-eastward, as Pennsylvania, New England, Nova Scotia, and Newfoundland,to be at the same time covered with clouds, and its a i r chilled and con-densed. The rarefied air being l ighter must r ise , and the denser air next toit will press into its place: that will be followed by the next denser air, thatby the next, and so on. Thus, when I have a fire in m y chimney, t h e r e is acurrent of air constantly flowing from the door to the chimney; but thebeginning of the motion was at the chimney, where the air being rarefiedby the fire rising, its place was supplied by the coole r ai r that was next toit, and the place of that by the next, and so on to the door . So the waterin a Iong sluice or mill-race, being stopped by a gate at one end, to let itout. the water next the gate begins firs t to move, t h a t which is next to it

3 2 8 H o u s l o n : [J. F. I.,

follows; and so, though the water proceeds forward to the gate , the motionwhich began t h e r e runs backwards, if one may so speak, to the upper endof the race, where the water is last in motion. W e have on this continent along ridge of mountains running from nor theas t to southwest; and thecoast runs the same course. These may contribute towards the directionof the winds, o r at least influence them in some degree. I f these conjec-tures do not satisfy you, I wish to have yours o n the subject."

A t a l a t e r d a t e ; i. e., M a y i2 , 1 7 6 o , in a l e t t e r t o A l e x a n d e rS m a l l , o f L o n d o n , F r a n k l i n w r i t e s as f o l l o w s :

"Agreeable to your request, I send you my reasons for thinking thatour Nor th -Eas t storms in Nor thAmer ica b e g i n first, in point of time, in theSouth-West par t s : T h a t is to say, t h e air in Georgia, the farthest of ourcolonies to the South-West, begins to move South-Westerly before the airof Carolina, which is the next colony North-Eas tward; the air of Carolinahas the same motion before the air of Virginia, which lies still more N o r t h -Eastward; and so on North-Easterly through Pennsylvania, New York , NewEngland, &c., qui te to Newfoundland.

"These Nor th -Eas t s t o r m s are generally very violent, continue some-t imes two o r t h r e e days, and often do considerable damage in the harboursa long the coast. They are attended with thick clouds and rain.

"Wha t firs t gave me this idea, was the following circumstance. Abouttwen ty years ago, a few more o r less, I c a n n o t from my m e m o r y be certain,we.were to have an eclipse of the moon at philadelphia, on a Friday even-ing, about nine o'clock. I intended to observe it, but was prevented by aNor th -Eas t storm, which came o n about seven with thick clouds as usual,t h a t qui te obscured the whole hemisphere. Yet when the post broughtus the Bos ton newspaper, g iving an account of the effects of the s t o r m inthose par ts , I found the beginning of the eclipse had been well observedthere, though Bos ton lies N. E. of Philadelphia about 4oo miles. Thispuzzled me, because the s t o r m began with us so soon as to prevent any ob-servation, and being a N. E. storm, I imagined it must have began r a t h e rsooner in places farther to the N o r t h Eastward, than it did at Philadelphia.I therefore mentioned it in a letter to m y broher , who lived in Boson ; andhe informed me that the s t o r m did begin with them till near eleven o'clock,so t h a t they had a good observation of the eclipse: and upon comparingall the o t h e r accounts I received from the several colonies, of the time be-ginning of the same s t o r m and since that of o t h e r storms of the same kind,I found the beginning to be always la te r the farther North-Eastward. Ihave not my no te s with me here in England, and cannot from memory, saythe proportion of time to distance, but I t h i n k it is about an hour to eve ryhundred miles.

"F rom thence I formed an idea of the cause of these storms, which Iwould explain by a familiar instance o r two. * * * Suppose a long canalof water stopp'd at the end of a gate. The water is qui te at rest till the~ate is open. then it begins t o move out through the gate; the water nextthe gate is first in motion, and moves towards the gate; the water next to

May, I9o6.] Franklin as aMan of Scienec and an Inve~#or. 329

that first water moves next, and so on successively, till the water at thehead of the canal is in motion, which is last of all. In this case all thewater moves indeed towards the gate, "out the successive times of beginningmotion are the contrary way, vi'z. from the gate backwards to the head ofthe canal. Again, suppose the air in a chamber at rest, no current throughthe room till you make a fire in the chimney. Immediately the air in thechimney being rarefied by the fire, rises; the air next the chimney flows into supply its place, moving towards the chimney; and, in consequence, therest of the air successively, quite back to the door. Thus to produce ourNorth-East storms, I suppose some great heat and rarefaction of air in orabout the Gulph of Mexico; the air thence rising has its place supplied bythe next more northern, cooler, and therefore denser and" heavier, air; that,being in motion, is followed by the next more northern air, &c., &c., in asuccessive current, to which current our coast and inland ridge of moun-tains give the direction of North-East, as they lie N. E. and S. W.

"This I offer only as an hypothesis to account for this particular fact;and, perhaps, on farther examination, a better and truer may be found. Ido not suppose all storms generated in the same manner. Our North-Westthunder-gust in America I know are not; but of them I have written myopinion fully in a paper which you have seen."

W h i l e unfortunately F r a n k l i n did not in this , as in manyo t h e r of his papers , give the e x a c t date of the eclipse, yet, sincethis date f i x e s the time when his attention was first d i r e c t e d t othe fact that the n o r t h e a s t s t o r m s of this c o u n t r y s t a r t in thesouthwest , P r o f . B a c h e , of the Universi ty of Pennsylvania, bym e a n s of a c a r e f u l s t u d y of all the eclipses of the moon k n o w nt o b a r e o c c u r r e d a t a b o u t this t i m e , h a s definitely f i x e d thedate a t O c t o b e r 2 I , 1743. This is a m a t t e r of nolittle scientific im-portance, s i n c e a c l a i m has been m a d e that the law of the m o v e -m e n t s of the n o r t h e a s t s t o r m s of the U n i t e d S t a t e s was firstpublished by a n o t h e r b e f o r e the time r e f e r r e d t o in the l e t t e r t oEliot . It s e e m s from this fact , therefore, that F r a n k l i n was thefirst discoverer of the i m p o r t a n t f a c t s c o n c e r n i n g the m o v e -m e n t s of the northeast storms.

T h e r e r e m a i n s yet a n o t h e r i m p o r t a n t subject in g e o g r a p h i c a lphysics that a t t r a c t e d F r a n k l i n ' s at tention at a comparativelye a r l y d a t e . I a l l u d e t o the e x i s t e n c e and c a u s e s of that g r e a tm o v i n g mass of h e a t e d w a t e r off the e a s t e r n c o a s t of the U n i t e dStates, k n o w n as the Gulf S t r e a m . H e g i v e s an a c c o u n t of thiss t r e a m in a l e t t e r t o D a v i d L e r o y , a t Paris, the l e t t e r b e a r i n gdate of August , 1785 :

"Vessels are sometimes retarded, and sometimes forwarded in their

3 3 ° H o u s t o n .. [J. F. I. ,

voyages, by currents at sea, which are often not perceived. (a) About theyear 1769 o r I67O, t h e r e was an application made by the Board of Cus toms atBoston, to the Lords of the Treasury in London , complaining that thepackets between Falmouth and New York were generally a fortnightlonger in the i r passages, than merchant ships from London to Rhode Is-land, and propos ing that for the future they should be ordered t o Rhode Is-land instead of New York . Being then concerned in the management ofthe American post-office, I happened to be consulted on the occasion; andit appearing strange to me, that t h e r e should be such a difference betweentwo places scarce a day's run asunder, especially when the merchant shipsare generally deeper laden, and more weakly manned than the packets, andhad from London the whole leng th of the r iver and channel to run beforethey left the land of England, while the packets had only to go from Fal-mouth, I could not but think the fact misunderstood o r misrepresented.(b) There happened then to be in London a Nantucket sea captain of my ac-quaintance, to whom I communicated the affair. He told me he believedthe fact migh t be t rue; but the difference was owing to this , that the RhodeIs land captains were acquainted with the Gulf Stream, which those of theEnglish packets were not. 'We are well acquainted with that stream,' sayshe, 'because in our pursuit of whales, which keep near the sides of it, butare not to be met with in it, we run down a long the sides, and frequentlycross it to change our sides; and in cross ing it have sometimes met andspoke with those packets, who wereWe have informed them that theyagainst them to the value of t h r e ecross it and get out of it; but theysimple Amer ican fishermen. When

in the middle of it, and stemming it.were stemming a cur ren t that wasmiles an hour ; and advised them towere too wise to be counselled bythe winds are but light,' he added,

'they are carried back by the cur ren t more than they are forwarded by thewind; and, if the wind be good, the subtraction of seventy miles a day fromthe i r course is of some importance.' (c) I then observed it was a pity no no-tice was t a k e n of this cur ren t upon the charts, and requested him to mark itout for me, which he readily complied with, adding directions for avoidingit in sai l ing from Europe to N o r t h America. I p rocured it to be engravedby order from the general post-office, on the old char t of the Atlantic, atMoun t and Page's, Tower Hill; and copies were sent down to Falmouthfor the captains of the packets, who slighted it however : but it is s inceprinted in France . of which edition I h e r e t o annex a copy. (See Fig. 12.)

(d) " T h i s stream is probably generated ~oy the great accumulation ofwater on the eas te rn coast of America between the tropics, by the tradewinds which constantly blow there. I t is known, that a large piece of waterten miles broad and generally only t h r e e feet deep, has by a s t r o n g windhad its waters dr iven to one side and sustained so as to become six feetdeep, while the windward side was laid dry. This may give some idea ofthe quantity heaped up on the Amer ican coast, and the reason of its run-ning down in a s t r o n g cur ren t through the islands into the Bay of Mexico,and from thence issuing through the Gulf of Florida, and proceeding a longthe coast to the banks of Newfoundland, where it t u r n s off towards andruns down through the Wes te rn Islands. Having since crossed this s t ream

May, I9o6.] Franklin as aMan of Scienec and an Inventor. 3 3 I

several t imes in pass ing between America and Europe , I have been atten-tive to sundry circumstances relating to it, by which to know when one isin it; and besides the gulf weed with which it is interspersed, I find that itis always warmer than the sea o n each side of it, and that it does notsparkle in the night. (e) I annex hereto the observations made with the ther-mometer in two voyages, and possibly may add a third. I t will appear fromthem, that the thermometer may be a useful instrument to a navigator,s ince currents coming from the nor thward into sou thern seas will probablybe found colder than the water of those seas, as the currents from thesou thern seas into the n o r t h e r n are found warmer. And it is not to bewondered, that so fast a 'body of deep warm water , several leagues wide,

Fig. 12. Franklin'sEarly Chartofthe Gulf Stream.

coming from between the t rop ics and issuing out of the gulf into the north-ern seas should re ta in its warmth longer than the twenty o r thirty daysrequired to its pass ing the banks of Newfoundland. The quantity is toogreat, and it is too deep to be suddenly cooled by passing under a coole rair. (f) The air immediately over it, however, may receive so much warmthfrom it as to be rarefied and rise, being rendered lighter than the air oneach side of the stream; hence those airs must flow in to supply the placeof the r is ing warm air, and, meeting with each other, form those tornadoesand waterspouts frequently met with, and seen near and over the stream;and as the v a p o r from a cup of t e a in a warm r o o m , and the brea th of ananimal in the same r o o m , are hardly visible, but become sensible im-• nediately when out in the cold air, so the v a p o r from the Gulf Stream, in

332 Houston : [J. F. I.,

warm latitudes, is scarcely visible, but when it comes into the cool airfrom Newfoundland, it is condensed into the fogs, for which those parts areso remarkable.

"The power of wind to raise water above its common level in the seais known to us in America, by the high tides occasioned in all our seaportswhen a strong northeaster blows against the Gulf Stream.

"The conclusion from these remarks is, that a vessel from Europe toNorth America may shorten her passage by avoiding to stem the stream,in which the thermometer will be very useful; and a vessel from Americato Europe may do the same bY the same means of keeping in it. It mayhave often happened accidentally, that voyages have been shortened bythese circumstances. It is well to have the command of them."

(a) An evident typographical error, from 1769 to 177o,

(b) A Nantucket Captain knew of the existence of the GulfStream. This old seaman asser ted that it was a matter of gen-eral information amo.ng the American whalers that the whaleskept near the sides of the S t r e a m , but did not enter it. Thesewhalers, therefore, ran along the sides of the Gulf Stream,sometimes cross ing it.

(c) Note here the utilitarian nature of Franklin. On obtain-ing this information he immediately takes the necessary s t epsfor calling the at tent ion of navigators to the existence of thisStream. At his request, the Captain m a r k s on a c h a r t its loca-t ion and general direction. Franklin, who is connected withthe administration of the Post Office in the S t a t e of Pennsyl-vania, has t h e s e markings engraved on an old c h a r t of the At -kmt ic Ocean, and sends copies to Fahnouth for the captains ofthe packets . A copy of one of t h e s e charts tha t was since print-ed in France, is shown in Fig. 12.

(d) Bearing in mind the time that this paper was written,Franklin's explanation as to the causes of the Gulf Stream maybe regarded as excellent.

(e) Note here Franklin's practical use of the thermometer inmapping out the posi t ion of the boundaries of the Gulf Stream,as well as his valuable suggestions as to the aid the thermome-ter is capable of affording navigators in such cases. Franklinpublished an account of measurements of the temperatureof the Gulf Stream made during a subsequent voyage, while onthe Pennsylvania Packet, Captain Osborne, from London toPhiladelphia, in April and May, 1775. D u r i n g t h e s e meas-

May, 19o6.1 Franklin as aMan of Scienec and an Inventor. 333

u r e m e n t s , s o m e i n t e r e s t i n g observations w e r e made as t o d e e psea t e m p e r a t u r e s . I n one instance, d u r i n g perfectly calmw e a t h e r an e m p t y bott le, t i g h t l y c o r k e d , was sent down t o thed e p t h of s o m e , t w e n t y f a t h o m s . On d r a w i n g it up, it was stillf o u n d t o be e m p t y . W h e n a g a i n let down t o a d e p t h of th i r ty-five f a t h o m s , the p r e s s u r e of the w a t e r h a d b e e n sufficientlyg r e a t t o f o r c e the cork i n t o the b o t t l e , so that w h e n the b o t t l ewas d r a w n t o the s u r f a c e it was f o u n d t o be filled with w a t e rat a t e m p e r a t u r e six d e g r e e s c o l d e r than that at the sur-face. I n a s o m e w h a t s i m i l a r m a n n e r , e x p e r i m e n t s madewith an e m p t y c a s k s h o w e d t h a t , a l t h o u g h some l e a k a g e oc-c u r r e d d u r i n g the d r a w i n g up of the c a s k , the w a t e r it con-t a i n e d was at a t e m p e r a t u r e of some 12 d e g r e e s c o l d e r than thes u r f a c e w a t e r .

(f) The e x p l a n a t i o n here g i v e n a s t o the p r o b a b l e c a u s e ofthe fogs so c o m m o n off the c o a s t of N e w f o u n d l a n d is the onethat is still g e n e r a l l y h e l d .

It was d u r i n g one of the many v o y a g e s b e t w e e n A m e r i c a andE u r o p e that F r a n k l i n i n v e n t e d an i m p o r t a n t d e v i c e k n o w n a sthe s w i m m i n g a n c h o r . This d e v i c e is of u s e in p r e v e n t i n g aship from d r i v i n g t o l e e w a r d in deep w a t e r , w h e r e t h e r e is nos o u n d i n g , and w h e r e , consequently, an o r d i n a r y a n c h o r c a n n o tbe e m p l o y e d . F r a n k l i n n a m e s the f o l l o w i n g characteristicsw h i c h s h o u l d be p o s s e s s e d by this type of a n c h o r :

(i) I t s s u r f a c e s h o u l d be of such a size t h a t , w h e n a t the endof the h a w s e r in the w a t e r , and p l a c e d perpendicularly, it s h o u l dso hold as t o b r i n g the s h i p ' s head t o the w i n d , in w h i c h s i t u a -t ion the w i n d h a s l e a s t p o w e r t o d r i v e the vessel.

(2) I t s h o u l d be a b l e , by i t s resistance, t o p r e v e n t the s h i p ' sr e c e i v i n g way.

(3) It s h o u l d be c a p a b l e of b e i n g p l a c e d b e l o w the h e a v e ofthe sea, but n o t b e l o w the u n d e r t o w .

(4) It s h o u l d not take up m u c h room in the ship.(5) It s h o u l d be c a p a b l e of b e i n g e a s i l y t h r o w n i n t o the

w a t e r and a s s u m i n g t h e r e i n i t s d e s i r e d posit ion, and s h o u l d af-t e r w a r d s be easy t o take i n t o the ship and stow a w a y .

F r a n k l i n d e v i s e d two of t h e s e a n c h o r s . O n e of them wasmade in the form of a k i t e , F ig . 13, w h i l e the o t h e r h a d the

334 t t o t t s t o n : [J. F. I.~

s h a p e of an u m b r e l l a . F r a n k l i n thus d e s c r i b e s the u m b r e l l atype of a n c h o r :

"The o t h e r machine for the same purpose is to be made more in theiotm of an umbrella, as represented in fiKure 14. The stem of the um-brella, a square spar of p r o p e r length, with four movable arms, of which twoare represented C, C, figure I4. These arms to be fixed in four jo in t cleats,as D, D, &c., one on each side of the spar , but so as that the four a r m smay open by tu rn ing on a pin in the joint. When open they form a crosson which a four-square canvass sail is to be extended, its corners fastenedto the ends of the four arms. T h o s e ends are also to be stayed by ropesfastened to the stem o r spar , so as t o keep them shor t of being at r igh tangles with it; and to the end of one of the arms should be hung the small

Fig. 13. Franklin's Swimming Anchor.

bag of ballast, and to the end of the opposite a rm the empty keg. This ,on being thrown into the sea, would immediately open; and when it hadperformed its function, and the s t o r m over, a small rope from its o t h e r endbeing pulled on, would turn it, c lose it, and draw it easily home to theship. This machine seems more simple in its operation, and more easilymanageable than the first, and perhaps may be as effectual."

A n o t h e r i m p o r t a n t i n v e n t i o n b e l o n g i n g t o a p p l i e d p h y s i c s ist o be f o u n d in w h a t is k n o w n as F r a n k l i n ' s P e n n s y l v a n i a F i r e -Place. The f o l l o w i n g d e s c r i p t i o n is g i v e n by F r a n k l i n :

"An Accountof the New-Invented

Pennsylvanian Fire-Place;wherein

T h e i r construction and manner of operation is particularly explained; t he i r

May, 19o6.] Frank l i~r a s a I U a l t o f S c i e n e c al~d a n Inven tor . 335

advantages above every o t h e r method of warming r o o m s demonstrated;and all objections that have been raised against the use of them answeredand obviated. With directions for putting them up, and for using to thebest advantage. And a copper-plate, in which the several parts of the ma-chine are exactly laid down, from a scale of equal par ts .

Philadelphia;Printed and sold by B. Franklin, I744."

"In thes t N o r t h e r n Colonies the inhabitants keep fires to sit by, gener-ally seven months in the year ; t h a t is, from the beginning of October , tothe end of Apri l ; and, some winters, near e ight months, by taking in par tof September and May.

"Wood, our c o m m o n fuel, which within these hundred years migh t behad at every man 's door , must now be fetched near one hundred miles t osome towns, and makes a very considerable article in the expence offamilies.

"As therefore so much of the comfort and conveniency of our lives,

Fig. 14. F r a n k l i n ' s S w i m m i n g A n c h o r , D e t a i l s ~.f.

for so great a part of the year, depends on the article of fire; s ince fuel isbecome so expensive, and (as the country is more cleared and settled)will of course grow scarcer and dearer , any new proposal for saving thewood, and for lessening the charge, and augmenting the benefit of fire bysome particular method of mak ing and managing it, may at least bethough t wor th consideration.

" T o avoid the several inconveniences, and at the same time reta in allthe advantages of o t h e r fire-places, was contrived the Pennsylvania Fire-Place, now to be described.

"This machine consists of"A bottom plate (i) (See Plate annexed, figure 15.)"A back plate, (if)"Two side plates , (iii iii)"Two middIe plates, (iv iv) which jo ined together, form a t igh t box,

with winding passages in it for warming the air."A front plate, (v)"A top plate, (vi)"These are all cast of iron, with mouldings o r ledges where the pla tes

336 H o z t s t o n .. [J. F. I.,

V

~c

t~

VI

Fig .18 . T h e P e n n s y l v e n i a

May, I9O6.] Franklin as aMan of Scienec and an Inventor. 337

0

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Fire-place.

VOL. CLXI, No. 965

o ©

22

,]3 8 f fozts lon ." [J. F. I..

come together, to hold them fast, and re ta in the m o r t a r used for pointingto make t igh t joints. When the plates are all in the i r places, a pair ofslender rods with screws, are sufficient to bind the whole very firmly to-gether, as it appears in A.

" T h e r e are, moreover, two thin plates Of wrought iron, viz.: the sut-ter, (vii) and the register, (viii); besides the screw-rods O P, all of whichwe shall explain in the i r order . -

"(i) The b o t t o m plate o r hearth-piece, is round before, with a r is ingmoulding that serves as a fender to keep coals and ashes from coming tothe floor, &c. I t has two ears, F G, perforated to receive the screw-rodsO P: a longair-hole, a a, through which the fresh o~tward air passes upinto the a i r -box ; and t h r e e smoke-holes B C through which the smokedescends and passes away; all represented by dark squares. I t has alsodouble ledges to receive between them the b o t t o m edges of the plate, thetwo side pla tes and the two middle plates . These ledges are about an inchasunder, and about half an inch h igh ; a profile of two of them jo ined to afi'agment of plate, appea r s in B.

"(ii) The back plate is without holes, having only a pair of ledges o neach side, to receive the back edge of the two.

"(iii iii) Side pla tes : These have each a pair of ledges t o receive theside-edges of the front plate, and a little shoulder for it to rest on; alsotwo pair of ledges to receive the side edges of the two middle plates whichform the air-box; and an oblong air-hole near the top, through which isdischarged into the room the air warmed in the alr-box. Each has also awing o r bracket, H and I, to keep in falling brands, coals, &c., and a smallhole, Q and R, for the axis of the regis ter t o tu rn in.

"(iv iv) The ai r -box is composed of the two middle plates DE and FG.The first has five thin ledges o r partitions east on it, two inches deep, theedges of which are received in so many pair of ledges east in the other.T h e tops of all the cavities formed by these thin deep ledges, are also eov-.ered by a ledge of the same form and depth, cast with t h e m ; so that whenthe plates are put t oge the r and the joints luted, t h e r e is n o communicationbewtween the ai r -box and the smoke. I n the winding passages of this box.fresh air is warm'd as it passes into the r o o m .

"(v) The front plate is arched on the under side, and ornamented withfoliages, &c. I t has no ledges.

"(vi) The top plate has a pair of ears ,M N, answerable to those in theb o t t o m plate, and perforated for the same purpose: I t has also a pair ofledges running round the under side, to receive the top edges of the front.back, and side plates. The ai r -box does not reach up to the top plate bytwo inches and half.

"(vii) The shu t t e r is of thin wrought iron and light, of such a length~nd breadth as to close well the open ing o f the fire-place. I t is used toblow up the fire, and to shut up and secure it at nights . I t has two brassl~nobs for handles, d d, and commonly slides up and down in a groove, leftin p~tting up the fire-place, between the foremost ledge of the side-plates,and the face of the front p la te ; but some chuse t o set it aside when it is n o ti t : use, and apply it o n occasion.

May, I9O6.] Franklin as aMan of Scienec and an Inventor. 3 3 9

"(viii) The regis ter is also of thin wrought iron. I t is placed betweenthe back plate and air-box, and can, by m e a n s of the key S, be tu rned on itsaxis, so as t o lie in any position between level and upright.

"The screw-rods O P are of wrought i ron , about a third of an inchthick, with a bu t ton at bottom, and a screw and nut at top, and may be or-namented with two small brasses screwed o n above the nuts.

"To put this Machine to work,"I. A false back of four inch (or, in shallow small chimneys, two inch)

brick work is to be made in the chimney, four inches o r more from the trueback: From the top of this false back a clos ing is to be made over to thebreast of the chimney, that no air may pass into the chimney, but whatgoes under the false back, and up behind it.

"2. Some br icks of the h e a r t h are t o be t a k e n up, t o form a hollowunder the b o t t o m plate across which hol low runs a th in t i gh t partition, tokeep apar t the air entering the hol low and the smoke; and is thereforeplaced between the air-hole and smoke-holes.

"3. A passage is made, communicating with the ou te r air, to introducethat air into the fore par t of the hollow under the bottom-plate, whence itmay rise t h r o ' the air-hole into the air-box.

"4- A passage is made from the back part of the hollow, communicat-ing with the flue behind the false back: Through this passage the smoke isto pass.

"The fire-place is to be e rec t ed upon these hollows~ by putting all thep la tes in the i r places, and screwing them together.

"Its operation may be conceived by observing the plate entitled, Profileof the Chimney and Fire-place. (Fig. I6.)

"M The mantel-piece or breast of the chimney."C The funnel."B The false back and closing." E True back of the chimney." T Top of the fire-place." F The front of it."A The place where the fire is made."D The air-box."K The hole in the side plate, through which the warmed air is dis-

charged out of the ai r -box into the .room."H The hollow filled with fresh air, entering at the passage I, and as-

cending into the ai r -box through the air-hole in the b o t t o m plate, near"G The partition in the hollow to keep the air and smoke apart." P The passage under the false back and par t of the h e a r t h for the

smoke."The arrows show the course of the smoke ."The fire being made at A, the flame and smoke will ascend and s t r ike

tile top T, which will thereby receive a considerable heat. T h e smoke, find-ing n o passage upwards, t u r n s over the top of the air-box, and descendsbetween it and the back plate to the holes at B, in the b o t t o m plate, heat-ing, as it passes, both plates of the air-box, and the said back-plate; thefront plate, b o t t o m and side plates , are also all heated at the same time.

340 H o g s l o n .. [J. F . I.,

The smoke proceeds in the passage that leads it under and behind the falseb~ck, and so rises into the chimney. The air of the r o o m , warmed behindthe back plate, and by the sides, front, and top plates , becoming specificallyl ighter than the o t h e r ai r in the r o o m , is obliged to rise; but the closureover the fire-place hinder ing it from going up the chimney, it is forced outinto the r o o m , rises by the mantle-piece to the ceiling, and spreads all overthe top of the r o o m , whence, being crouded down gradually by the s t reamnewly-warm'd air that follows and rises above it, the whole room becomesin a shor t time equally warmed.

"At the same time the air, warmed under the bottom-plate, and in the

. /

F ig . 16. P r o f i l e o f t h e P e n n s y l v a n i a C h i m n e y a n d F i r e Place.

air-box, rises and comes out of the holes in the side-plates, very swiftly ifthe door Of the room be shut, and joins its current with the s t ream beforementioned, r is ing from the side, back, and top plates.

"The air that enters the room through the ai r -box is fresh, thoughwarm; and, computing the swiftness of its m o t i o n with the areas of theholes, it is found that near ten barrels of fresh air are hourly introducedby the air-box; and by this m e a n s the air in the room is continuallychanged, and kept, at the same time, sweet and warm.

" I t is t o be observed, that the entering air will not be warm at firs tlighting the fire, but heats gradually, as the fire increases.

" A square opening for a trap-door should be left in the clos ing of thechimney, for the sweeper to go up: The door may be made of state o r tin,

May, 1 9 o 6 . ] Franklin as aMan of Scienec and an Inventor. 34x

and commonly kept close shut, but so placed as that turning up against theback of the chimney when open, it closes the vacancy behind the false back,and shoots the soot, that falls in sweeping, out upon the hearth. Thistrap-door is a very convenient thing.

" I n r o o m s where much smoking of tobacco is used, it is also conveni-ent to have a small hole, about five o r six inches square, cut near the ceil-ing through into the funnel: This hole must have a shutter, by which itmay be clos 'd or open'd at pleasure. When open, t h e r e will be a s t r o n gdraught of air t h r o ' i t into the chimney, which will presently ca r ry off acloud of smoke, and keep the room clear : If the room be too hot likewise,it will ca r ry off as much of the warm air as you please, and then you maystop it entirely, or in part, as you t h i n k fit. By this means it is, that thetobacco smoke does not descend a m o n g the heads of the company near thefire, as it must do before it can get into c o m m o n chimneys. ?

" T H E M A N N E R OF U S I N G T H I S FIRE-PLACE.

"Your cord-wood must be cut into t h r e e lengths ; or else a shor t piece,fit for the fire-place, cut off, and the longer left for the kitchen or otherfires. Dry hickory, o r ash, or any woods that burn with a clear flame arer a t h e r to be chosen, because such are less apt to foul the smoke-passageswith s o o t ; and flame communicates with its light, as well as by contact,grea te r heat to the plates and room. But where more ordinary wood isused, half a dry faggot of brush-wood, burnt at the firs t mak ing of fire inthe morning is very advantageous, as it immediately, by its sudden blaze,heats the plates and warms the room (which with bad wood slowly kindlingwould not 'be done so soon) and at the same t ime , by the leng th of itsflame, tu rn ing in the passages, consumes and cleanses away the soot thatsuch bad smoky wood had produced there in the preceding day, and so keepsthem always free and clean.--When you have laid a little back log, andplaced your billets o n small dogs, as in c o m m o n chimneys, and put somefire to t h e m , then slide down your shu t t e r as low as the dogs, and theopening being by that means contracted, the air rushes in briskly, andpresently blows up the flames. When the fire is sufficiently kindled, slideit up again. I n some of these fire-places t h e r e is a little six-inch squaretrap-door of thin wrought iron or brass, covering a hole of like dimensionsnear the fore-part of the bottom-plate, which being by a ring lifted uptowards the fire, about an inch, where it will be retained by two springingsides fixed to it perpendicularly, (See fig. 16, C, as above), the air rushesin from the hol low under the bottom plate, and blows the fire.Where this is used, the shu t t e r serves only to close the fire at nights. Themore forward you can make your fire on the hearth-plate, not t o be in-commoded b.y the smoke, the sooner and more will the room be warmed.At n igh t when you go to bed, cove r the coal o r brands with ashes, as usual;then take away the dogs, and slide down the shutter close to the bottom-plate, sweeping a little ashes against it, that no air may pass under it; thenturn the register, so as very near to stop the flue behind. If no smokethen comes out at crevices into the room, it is r i gh t : If any smoke is

3 4 2 t t o u s t o n ." [J . F. I. ,

perceived to come out, move the regis ter so as t o give a little draft, andit will go the r igh t way. Thus the r o o m will be kept warm all n i g h t ; forthe chimney being almost entirely stopt, very little cold air, if any, wille n t e r the room at any crevice. When you come to re-kindle the fire in themorning, turn open the regis ter before you lift up the slider, otherwise, ift h e r e be any smoke in the fire-place, it will come out into the r o o m . Bythe same use of the shutter and register, a blazing fire may be presentlystifled as well as secured, when you have occasion to leave it for any t ime:and at your re tu rn you will find the brands warm, and ready for a speedyre-kindling. The shu t t e r a lone will not stifle a fire, for it c a n n o t well bemade to fit so exactly but that a i r will enter, and that in a violent stream,sq as to blow up and keep alive the flames, and consume the wood. if thedraught be not checked by tu rn ing the regis ter t o shut the flue behindThe regis ter has also two o t h e r uses. If you observe the draught of air intoyour fire-place to be s t ronger than is necessary, (as in extreme coldweather it often is), so that the wood is consumed faster than usual; inthat case, a quarter, half, or two-thirds turn of the regis ter wilt check theviolence of the draught, and let your fire ,%urn with the moderation youdesire: And at the same time both the fire-place and the room will bewarmer, because less cold air will e n t e r and pass through t h e m . And if thechimney should happen to take fire, which indeed t h e r e is very little dangerof, if the preceding directions be observed in mak ing fires, and it be wellswept once a year ; for, much less wood being burnt, less soot is propor-tionately made; and the fuel being blown into flame by the shu t t e r (or thetrap door bellows) t h e r e is consequently less smoke from the fuel to makes o o t ; then, though the funnel should be foul, yet the sparks have such acrooked up and down round about way to go, that they are out beforethey get at it. I say, if ever it should be on fire, a turn of the regis tershu t s all close, and prevents any air going into the chimney, and so thefire may be easily stifled and mastered."

T H E ADVANTAGES OF T H I S FIRE-PLACE.

"Its advantages above the c o m m o n fire-places are,"I. That your whole room is equally warmed, so that people need not

close round the fire, rbut may sit near the window, and have the benefit ofthe l ight for reading, writing, needlework, etc. They may sit with com-fort in any par t of the room, which is a very considerable advantage in alarge family, where t h e r e must often be two fires kept, because all c a n n o tconveniently come at one.

"2. If you sit near the fire, you have not t h a t cold draft of uncomfort-able ai r nipping your back and heels, as when before c o m m o n fires, bywhich y o u may catch cold, being scorched before, and, as it were, frozebehind.

"3. If you sit against a crevice, t h e r e is not that sharp draft of coldair playing on you, as in r o o m s where t h e r e are f i res in the c o m m o n way;by which many catch cold, whence proceed coughs, eatarrhs, tooth-aches,fevers, pteurisies, and many o t h e r diseases.

May, 19o6.] F r a n k l i n a s a M a n o f S c i e n e c a n d a n Inven tor . 3 4 3

"4. I n case of sickness, they make most excellent nurs ing-rooms; asthey constantly supply a sufficiency of fresh air, so warmed at the sametime as to be n o way inconvenient o r dangerous. A small one does wellin a chamber; and, the chimneys being fitted for it, i t may be removed fromone room to another, as occasion requires, and fixed in half an hour . Theequal temper, too, and warmth of the air of the room is though t to be'particularly advantageous in some distempers; for it was observed in thewinters of 173o and I736, when the small-pox spread in Pennsylvania, thatvery few children of the Germans died of that distemper in proportion t othose of the English;-which was ascribed, by some, to the warmth and equalt e m p e r in the i r stove rooms, which made the disease as favorable as itcommonly is in the West Indies. But this conjecture we submit to thejudgment of physicians.

"5. I n common chimneys, the s t rongest heat from the fire, which isupwards, goes directly up the chimney, and is l o s t ; and t h e r e is such as t r o n g draft into the chimney, that not only the upr ight heat, but also theback, sides, and downward h e a t s are carried up the chimney by that draftof air ; and the warmth given before the fire, by the rays that strike outtowards the r o o m , is continually dr iven back, crowded into the chimney,and car r ied up by the same draft of air. But here the upr ight heat strikesand heats the top plate, which warms the air above it, and that comes intothe room. The heat likewise, which the fire communicates to the sides,back, bottom, and air-box, is all brought into the r o o m , for you will finda constant amoun t of warm air coming out of the chimney corne r into ther o o m . Hold a candle just under the mantle-piece, o r 5feast of your ch im-ney, and you will see the flame bend outwards; by laying a piece of smokingpape r .on the hearth, on either side, you may see how the cur ren t of airmoves, and where it tends, for it will turn and car ry the smoke with it.

"6. Thus, as very little of the heat is lost, when this fire-place is used,much less wood will serve you, which is a considerable advantage wherewood is dear .

"7. W h e n you burn candles near this fire-place, you will find that theflame burns qui te upright, and does not blare and run the tallow down, bydrawing towards the chimney, as against c o m m o n fires.

"8. This fire-place cures most smoky chimneys, and thereby preservesboth the eyes and furniture.

"9- I t prevents the fouling of chimneys; much of the lint and dustthat contributes to foul a chimney being, by the low arch , obliged to passthrough the flame, where it is consumed. Then, less wood being burnt,t h e r e is less smoke made. Again, the shutter, or trap-bellows, soon blow-it:g the wood into a flame, the same wood does not yield so much smokeas if burnt in a common chimney; for, as soon as the flame begins, smokein proportion ceases.

"IO. And, if a chimney should be foul. it is much less likely to takefire. I f it should take fire, it is easily stifled and extinguished.

" i i . A fire may be very speedily made in this fire-place by the help ofthe shutter, o r trap-bellows, as aforesaid.

\

344 t t o u s t o n .. [J. F. I.,

"12. A fire may be soon extinguished by closing it with the shu t t e rbefore, and tu rn ing the regis ter behind, which will stifle it, and the brandswill remain ready to rekindle. -

"13. The room being once warm, the warmth may be retained in it all• night.

"I4. And lastly, the fire is so secured at night, t h a t not one spark canfly out into the room to do damage.

" W i t h all these conveniences, you do not lose the pleas ing sight nor useof the fire, as in the Dutch ovens, but may boil the t e a kettle, warm the£at irons, heat heaters, keep warm a dish of victuals by setting it on thetop, etc.

C o n c e r n i n g the o p e r a t i o n of the P e n n s y l v a n i a F i r e - P l a c e ,F r a n k l i n r e m a r k s :

"Hav ing in 1742, invented an open s tove for the better warming ofrooms, and at the same time saving fuel, as the fresh air admitted waswarmed in entering, I made a present of the model to Mr. Robert Grace,one of my early friends, who, hav ing an iron furnace, found the cas t ing ofthe plates for these stoves a profitable thing, as they were growing indemand. T o promote that demand, I w r o t e and published a pamphlet,intitled "An Account of the new-invented Pennsylvania Fire-Places," &c.This pamphlet had a good effect. Governor T h o m a s was so pleasedwith the construction of this stove, as described in it, that he offered togive me a patent for the sole vending of them for a term of years ; but Ideclined it from a principle, which has ever weighed with me on such occa-sions, viz: That, as we enjoy great advantages from the inventions of othersl weshould be glad of an opportunity to serve others by any invention of ours;and this we should do freely and generously.

"An i ronmonger in London, however, assuming a good deal of mypamphlet, and working it up into his own, and mak ing some small changesin the machine, which r a t h e r hurt its operation, got a patent for it there,and made, as I was told, a little fortune by it. And this is not the onlyinstance of patents taken out of m y inventions by others , though not alwayswith the same success; which I neve r contested, as hav ing no desire ofprofiting by patents myself, and h a t i n g disputes. The use of these fire-places in very many houses, both here and in Pennsylvania, and the neigh-bor ing states, has been, and is, a great saving of wood to the inhabitants."

In connection with his i n v e n t i o n of s t o v e s , F r a n k l i n gavec o n s i d e r a b l e a t t e n t i o n t o the c o n s t r u c t i o n of c h i m n e y s . In al e t t e r t o J o h n I n g e n h o u s z , at V i e n n a , A u g u s t 28, 1785, F r a n k -lin d e s c r i b e s at l e n g t h the d i f f e r e n t w a y s in w h i c h c h i m n e y s,_nay be c a u s e d t o s m o k e , and also points ou t the m e a n s byw h i c h this s m o k i n g m a y b e s t be a v o i d e d •

It will be impracticable, on a c c o u n t of lack of space, t o dis-cuss this l e t t e r at l e n g t h . I t will suffice if some of the more

~ay, I9o6.] Franklin as aMan of Scienec and an Inventor. 345

important of the causes of s m o k y chimneys are pointed out.These are given by Franklin as follows:

(I) S m o k y chimneys are frequently produced in new housesby the mere want of air.

(2) S m o k y chimneys are frequently caused by the Opening,into the room being too large; tha t is, too wide, too high, o rbo th .

(3) S m o k y chimneys may be caused by too short a chimneyfunnel. This happens necessarily w h e r e a chimney is re-quired in a low building, since, if the funnel is raised high abovethe roof in order to s t rengthen the draught , it is in danger ofbeing blown down.

(4) S m o k y chimneys may be caused by one chimney over-powering another, where, for example, two chimneys exist inone large room and fires are made in bo th , the doors and win-dows being shut, the greater and s t ronger fire will overpowerthe weaker, drawing the air-down its funnel to supply its de-mands, wh i l e air descending the funnel connected with the~veaker fire will drive its s m o k e into the r o o m .

(5) S m o k y chimneys may also be caused by the tops of thechimneys being commanded by higher buildings, o r by a hill,so that the wind, blowing over such eminences, falls like waterover a dam, thus beating the s m o k e down the chimney.

(6) S m o k y chimneys are sometimes caused by the chimneyl~eing lower than the top of a near-by house , the wind being de-flected from the h o u s e and forced down the chimney.

O t h e r causes are given, bu t t h e s e are the most important.

At a later date, F r a n k l i n describes another form of s tovesuitable for burning pit coal. In this form of stove the con-struct ion is such that the s m o k e itself is consumed. A paperdescribing this s tove was read before the American Philosophi-cal Society on the 28th of January, I786. As will be seen, thiss tove is based on the principle of an inverted draught downthrough the burning material:

"Towards the end of the last century, an ingenious French philoso-pher, whose name I am sorry I cannotrecollect, exhibited an experiment toshow, that very offensive things might be burnt in the middle of a chamber,such as woolen rags, feathers, &c., without creating the least smoke orsmell. The machine in which it was made, if I remember right, was of:this form, (Plate XV, Fig. I7, No. I), made of plate iron. Some clear

346 H o u s t o n .. [J. F. I.,

.NO. I

A

N 0 . 2

. . . . . . C S

No. 5

NO. 3

N o . 6

=~70, 4 NO. 12

h

N o . 9

N o , 10

N o . 11

I

Fig. 17. D e t a i l s o f t h e P e n n s y l v a n i a Fire-place.

May, I 9 o 6 . ] Franklin as aMan of Scienec and an Inventor. 3 4 7

burning charcoals were put into the opening of the shor t tube A, and sup-ported t h e r e 'by the g r a t e B. The air, as soon as the tubes grew warm,would ascend in the longer leg C, and go out at D, consequently air mustenter at A, descending to B. I n this course it must be heated by theburning coals through which it passed, and rise more forcibly in the longertube, in proportion to its degree of heat o r rarefaction, and length of thattube. For such a machine is a kind of inverted siphon; and, as the grea te rweight of water in the longer leg of a c o m m o n siphon in descending isaccompanied by an ascen t of the same fluid, in the shorter; so, in this in-verted siphon, the grea te r quantity of levity of air in the longer leg, inrising is accompanied by the descent of ai r in the shorter. The th ings tobe burned being laid on the hot coals at A, the smoke must descendthrough those coals, and be converted into flame, which, after destroyingthe offensive smell, came out at the end of the longer tube as mere heatedair.

"Whoever would repeat this experiment with success, must take carethat the part A B, of the shor t tube, be quite full of burning coals, so thatne part of the smoke may descend and pass by them without goingthrough them, and being converted into flame; and that the longer tube beso heated as that the current of ascending hot air is esablished in it beforethe th ings t o be burnt are laid on tl]e coals; otherwise there will be a dis-appointment."

"The stove I am about to describe was also formed on the idea givenby the FrenCh experiment, and completely carried into execution beforeI had any knowledge of the German invention;! which I wonder should re-main so many years in a country, where men are so ingenious in the man-agement of fire, without receiving long since the improvements I havegiven it.

Description of the Par t s .

"A, the b o t t o m plate which lies flat upon the hearth, with its partitions,I, 2, 3, 4, 5, 6, (Plate, our fig. t7, No. 2) to slide the b o t t o m edges of thesmall plates Y, Y, No. i2; which pla tes mee t ing at X, close the front.

" B I, No. 3, is the cover plate showing its under side, with thegrooves I, 2, 3, 4, 5, 6, to receive the top edges of the partitions thatare fixed to the b o t t o m plate. I t shows also the grate W W , the bars ofwhich are cast in the plate, and a groove VV, which comes r igh t overthe groove Z Z, No. 2, receiving the upper edges of the small slidingplates Y Y, No. I2.

"B 2, No. 4, shows the upper side of the same a)late with a square im-pression o r groove for receiving the b o t t o m mouldings T T T T of thethree-sided box C, No. 5, which is cast in one piece.

"D, No. 6, its cover, showing its under side with grooves to receive theupper edges S S S of the sides of C, No. 5, aIso a groove R R, which, whentlle cover is put on, comes r igh t over another, Q Q in C, No. 5, betweenwhich is to slide.

"E, No. 7, the front plate of the box.

348 H o u s t o n : [J. F. I.,

"P, a hole three inches diameter through the cover D, No. 6, over whichhole stands the vase F, No. 8, which has a corresponding hole two inchesdiameter, through its bottom.

"The top of the vase opens at O O O, No. 8, and turns back upona hinge behind, when coals are to be put in; the vase has a grate withinat N N of cast iron H, No. 9, and a hole in the top one and a half inchesin diameter, to admit air, and to receive the ornamental brass gilt flamel~I, No. IO, which stands in that hole, and being itself hollow and open,suffers air to pass through it to the fire.

"G, No. ii, is a drawer of plate iron, that slips in between the partitions2 and 3, No. 2, to receive the falling ashes. It is concealed when the smallsliding plates Y, Y, No. Ie, are shut together.

"I I I I, No. 8, is a niche bmlt of brick in the chimney, and plastered.It closes the chimney over the vase, but leaves two funnels, one ineach corner, communicating with the bottom box K K, No. z."

As w e have r e p e a t e d l y s e e n , F r a n k l i n was essentially a utili-t a r i a n . W h e r e v e r possible, he set h i m s e l f the task of directlyapplying the principles of any g r e a t n a t u r a l law he had dis-c o v e r e d t o some useful purpose . W e see this in his g r e a t in-v e n t i o n of the l i g h t n i n g rod. It is also t o be o b s e r v e d in hisinvention of the Pennsylvania Fire-place, as well a s the stovewi th the d o w n w a r d d r a u g h t , that was c a p a b l e of b u r n i n g in ac!osed r o o m , not only pit c o a l , but even substances fhat would,in a n o r d i n a r y stove, give out e i t h e r e x c e e d i n g l y d i s a g r e e a b l eo r n o x i o u s o d o r s , or b o t h .

T o the same t y p e of investigation is F r a n k l i n ' s s t u d y of the "Gulf S t r e a m . N o s o o n e r does he hear of the e x i s t e n c e of thiss t r e a m of h e a t e d w a t e r , flowing as it does a l o n g thee a s t e r n c o a s t of the U n i t e d States, in the d i r e c t p a t h of vesselssailing b e t w e e n A m e r i c a and E u r o p e , than h e sets himself thetask of h a v i n g a c h a r t d r a w n of this body of w a t e r , w h i c h hehas e n g r a v e d , s e n d i n g c o p i e s t o such p a r t s of the w o r l d asw o u l d be most l i k e l y t o be of benefit , thus e n a b l i n g a n a v i -g a t o r t o turn what h a d been an evil, so far as it r e t a r d e d thes p e e d of his vessel when sailing in c e r t a i n directions, in to ana d v a n t a g e when sailing in oppos i t e directions. A g a i n , w h i l e

• this practical philosopher is e m p l o y i n g the t h e r m o m e t e r in de-t e r m i n i n g the limits of the Gulf S t r e a m , h e points out how suchuse m a y possibly be of v a l u e t o o t h e r n a v i g a t o r s in t e a c h i n gthem how t o a v o i d cold c u r r e n t s in the N o r t h e r n H e m i s p h e r e ,which, as is well k n o w n , g e n e r a l l y tend t o move from the n o r t ht o w a r d s the south.

May, 19o6.] Franklin as aMen of Scie~wc a~d an Inventor. 349

It was in this line of applied physics that F r a n k l i n made thestudy of the effects produced on the comfort of the individualensured by wearing woolen clothes in cold wintry weather,and linen clothes in hot summer weather. In a let ter to JohnLining, of Charlestown, South Carolina, dated New York ,April I4, 1757, he treats of a variety of topics, mainly, however,relating to the cold produced by evaporat ion. I t is in thislet ter tha t he thus speaks of the effect produced by clothing:

"Thus, as by a constant supply of fuel in a chimney, you keep a roomwarm, so, by a constant supply of food in the stomach, you keep a warmbody; only where little exercise is used, the heat may possibly be con-ducted away too fast; in whichcase such materials are to be used for clothingand 'bedding, against the effects of an immediate contact of the air, as are,in themselves, bad conductors of heat, and, consequently, prevent its beingcommunicated thro' their substance to the air. Hence what is calledwarmth in wool, and its preference, on that account, to linnen; wool notbeing so good a conductor: And hence all the natural coverings of ani-mals, to keep them warm are such as to retain and confine the natural heatit. the body, by being bad conductors, such as wool, hair, feathers, and thesilk by which the silk worm, in its tender embrio state, is first cloathed.Cloathing thus considered does not make a man warm by giving warmth,but by preventing the too quick dissipation of the heat produced in hisbody, and so occasioning an accumulation."

Franklin here gives the true explanation o f the source ofanimal heat as the food consumed by the animal. He pointsout the fact tha t clothing does not itself supply heat to thebody, bu t m e r e l y prevents the too r a p i d loss o~ the heat pro-duced by the animal's food. By employing as clothing suchpoor conductors as wool o r fur, the heat of the body is pre-~ented from being rapidly passed into the surrounding air.Wool may properly be called warm because it is a poor con-duc tor of hea t , bu t no t because it possesses any heat in itself.Linen, on the contrary, produces a cooling effect in that it per-mits the heat of the body to be rapidly passed or conductedthrough it to the surrounding air.

Franklin gave considerable thought to the effect of externalheat on the temperature of the bodies of heal thy animals. Henotices the fact tha t it is possible for a healthy living animal tobe exposed to a very high temperature without any notableincrease in its temperature. In another let ter to John Lining,of Charlestown, dated London, June 17, 1758, he gives an ac-

3 5 0 Houston: [J. F. I.,

count of an exceedingly hot Sunday that occurred in Philadel-phia in June, I75O, with the thermometer at IOO° in the shade :

"May not several phenomena hitherto unconsidered, o r unaccountedfor be explained by this property? (a)Dur ing the hot Sunday at Phila-delphia, in June, I75O, when the thermometer was up at ioo in the shade,I sat in my chamber without exercise, only reading o r writing, with noo t h e r cloathes on than a shirt, and a pair of long linen drawers, the win-dows all open, and a brisk wind blowing through the house, the sweatran off the backs of my hands, and my shir t was often so wet, as to induceme to call for dry ones t o put on; in this situation, one migh t have ex-pected, that the natural heat of the body 96, added to the heat of the airioo, should jo in t ly have created o r produced a much grea ter degreeof heat in the body; but the fact was, that my body never grew so hot asthe air that surrounded it, o r the immediate bodies immers 'd in the sameair. For I remember well that the desk, when I laid m y arm upon it; achair, when I sat down in it; and a dry shir t out of the drawer, when I putit on, all felt exceeding warm to me, as if they had been warmed before afire. And I suppose a dead body would have acquired the temperature ofthe air, though a living one, by continual sweating, and by the evapora-tion of that sweat, was kept cold.

"(b) May not this be a reason why our reapers in Pennsylvania,working in the open field in the clear, hot sunshine c o m m o n in our har-vest time, find themselves well able to go through that labor , withoutbeing much incommoded by the heat, while they cont inue to sweat, andwhile they supply matter f o r keep ing up that sweat, by dr inking frequentlyof a thin, evaporable liquo-, water mixed with rum; but, if the sweat s tops,they drop , and sometimes die suddenly, if a sweat ing is not again broughton by dr inking that l iquor, or, as some r a t h e r choose in that case, a kindof hot punch, made with water , mixed with honey, and a considerable pro-portion of vinegar? May t h e r e not be in negroes a quicker evaporationof the perspirable matter from the i r skins and lungs, which, by coolingthem more , enables them to bear the sun's heat be t t e r than whites do?(if that is a fact, as it is said to be; for the alleged necessity of havingnegroes, r a t h e r than whites, to work in the West India fields, is foundedupon it,) though the co lo r of the i r skins would otherwise make them moresensible of the sun's heat, s ince black cloth heats much sooner and more,i.n the sun, than white cloth. I am persuaded, from several instances hap-pen ing within my knowledge, that they do not bear cold weather so wellas the whites; they will perish when exposed to a less degree of it, andare more apt to have the i r limbs frost-bitten; and may not this be from thesame cause?"

(a) Franklin notes correctly the fact tha t , a l though the ther-m o m e t e r was IOO° in the shade, and his clothing was of such anature as to readily expose the body to the external air,nevertheless the temperature of his body did not greatly ex-

May, 19o6.] Franklin as aMan of Scienec and an Inventor. 35 t

t e e d i ts n a t u r a l temperature, n e v e r , in fact , g r o w i n g as hot asthe s u r r o u n d i n g air; for, as he r e m a r k s , his body was evidentlyc o l d e r than the desk on w h i c h he laid his arm, was c o l d e r thanthe c h a i r he sat on, or the dry s h i r t that h e took out of the-drawer t o r e p l a c e the wet one he had on. H i s r e f e r e n c e t o the.effect that a h igh t e m p e r a t u r e w o u l d p r o d u c e on a dead bodyis also in a c c o r d a n c e wi th well k n o w n facts. I t is possible for.a man t o go in to an o v e n , the t e m p e r a t u r e of w h i c h is suffi-~:iently h igh t o bake a t r u s s e d fowl, w h i c h he c a r r i e s in wi thhim, and t o safely r e m a i n in such a n oven u n t i l the fowl ist h o r o u g h l y c o o k e d , and then t o come out u n h a r m e d . F r a n k -l i n ' s explanation is c o r r e c t as t o the c a u s e ; viz. , that the l i v i n gbody protects itself by p e r m i t t i n g the h e a t t o evaporate them o i s t u r e it is constantly throwir tg out t o the surface, a n d thusp r e v e n t it from e n t e r i n g the body .

(b) The e x p l a n a t i o n c o n c e r n i n g the Pennsylvania r e a p e r s is~also correct . T h e i r sa fe ty , w h i l e u n d e r e x p o s u r e t o the hot sun,~ e n s u r e d by d r i n k i n g c o p i o u s d r a u g h t s of w a t e r , the r u m b e i n gvery likely a m a t t e r of taste , r a t h e r than of necessi ty .

In a n o t h e r letter, d a t e d S e p t e m b e r 2 o t h , 1761, t o a MissMary Stevenson, F r a n k l i n refers t o the e f f e c t p r o d u c e d by thes u n ' s r a y s on c l o t h e s of different c o l o r s as follows:

"(a) As to our other subject, the different degrees of heat imbibedfrom the sun's rays by cloths of different colours, since I cannot find thenotes of my experiment to send you, I must give it as well as I can from"memory.

( b ) "But first let me mention an experiment that you can easily makeyourself. Walk but a quarter o'f an hour in your garden when the sunshines, with a part of your dress white, and a part black; then apply yourhand to them alternately, and you will find a very great difference in~,armth. The black will be quite hot to the touch, the white still cool.

( e ) Another. Try to fire paper with a burning-glass. If it is white,.you will not easily burn it; but if you bring the focus to a black spot, orupon letters, written or printed, the paper will immediately be on fire~under the letters.

"Thus fullers and dyers find black cloths, of equal thickness with whiteones, and hung out equally wet, dry in the sun much sooner than the white,being more readily heated by the sun's rays. it is the same before a fire;the heat of which sooner penetrates black stockings than white ones, andso is apt sooner to burn a man's shins. Also beer much sooner warms ina black mug set before the fire, than in a white one, or in a bright silvertankard.

352 Houston: [J. F. I.~

( d ) "My experiment was this . I took a number of l i t t l e squarepieces of broad cloth from a taylor's pattern card, of various colours.T h e r e were black, deep blue, l ighter blue, green, purple , red, yellow, white,and all o t h e r colours, o r shades o f colours. I laid them all upon the snowin a bright, sun-shiny morning. I n a few hours (I cannot now be exactas to the t ime) the black being warmed most by the sun was sunk so lowas to be ~oelow the s t roke of the sun's rays; the dark blue almost as low,the l ighter blue not qui te so much as the dark, the o t h e r colours less asthey were lighter; and the quite white remained on the surface of the snow,not hav ing entered it at all.

( e ) "Wha t signifies philosophy that does not apply to some use? ~1aywe not learn from hence, that black clothes are not so fit to wear in ahot sunny climate or season, as white ones; because in such clothes thebody is more heated by the sun when we walk abroad, and are at the sametime h e a t e d by the exercise, which double heat is apt to br ing on putr iddangerous fevers? That soldiers and seamen who must march and labour-in the sun, should in the East o r West Indies have a uniform of white?That summer hats for men o r women should be white, as repelling thatheat which gives headaches t o many, and to some the fatal s t roke that t h eFrench call the Coup de Soleil? That the ladies Summer hats , however,should be lined with black, as not reverberating on the i r faces those rayswhich are reflected upwards from the e a r t h o r water? T h a t the putting ofa white cap of pape r o r linen within the crown of a black hat, as some do,.will not keep out the heat, tho' it would if p lac 'd without. T h a t fruit wallsbeing blacked may receive so much heat from the sun in the daytime, asto cont inue warm in some degree t h r o ' the night, and there~by preservethe fruit from frosts, o r forward its growth? With sundry o t h e r particulars.of less o r grea te r importance, that will occur from time to time to inat-tentive minds?"

(a) It will be n o t i c e d that this i n v e s t i g a t i o n is not u n l i k e ap r i o r investigation in w h i c h F r a n k l i n p o i n t e d ou t the e f f e c t sp r o d u c e d on the t e m p e r a t u r e of the h u m a n b o d y , a r i s i n g fromthe u s e of t e x t i l e f a b r i c s that variec~ in t h e i r p o w e r of c o n d u c t -ing or t r a n s f e r r i n g h e a t . H e r e , h o w e v e r , the i n v e s t i g a t i o nr e f e r s only t o the influence of the c o l o r of f a b r i c s on t h e i rabili ty t o take in heat from a n e x t e r n a l s o u r c e , such a s the sun.

(b) A s i m p l e but c r u c i a l experiment . A f t e r an e x p o s u r eof say a q u a r t e r of a n h o u r t o the hot sun, the fact that differ-ent por t ions of the c l o t h i n g will have b e e n differently h e a t e da c c o r d i n g t o t h e i r c o l o r , can be r e a d i l y d e t e r m i n e d bys i m p l y t o u c h i n g the 'different a r t i c l e s of d r e s s , w h e n thed a r k e r c o l o r e d ones will be f o u n d t o be m u c h w a r m e r than thel i g h t c o l o r e d o n e s .

(c) This e m p l o y m e n t of a b u r n i n g g l a s s or c o n v e x l e n s " i s

May, 19o6.] Franklin as aMan o[ Scienec and an Inventor. 353

very simple, but q u i t e c o n v i n c i n g . B l a c k p a p e r can be e a s i l yfired or b u r n e d by the concentrated s o l a r f o c u s of the b u r n i n gg l a s s , w h i l e w h i t e p a p e r cannot .

(d) A c h a r m i n g experiment , j u s t of the c h a r a c t e r that wes h o u l d e x p e c t this t r u e p h i l o s o p h e r t o m a k e . Wi th n o o t h e rm e a n s than s i m p l e s q u a r e s of d i f f e r e n t c o l o r e d c l o t h s of thesame size for the m a t e r i a l s w h i c h are t o be e x p o s e d t o the s u n ' sh e a t , and with n o o t h e r t h e r m o m e t r i c a p p a r a t u s than theg r o u n d c o v e r e d with a l a y e r of s n o w , an e x c e l l e n t test is m a d e .F r a n k l i n p l a c e s the s q u a r e s of c lo th on the s n o w , and e x p o s e sthem for a few h o u r s t o the r a d i a t i o n of the sun. The factthat d i f f e r e n t t e m p e r a t u r e s have b e e n a t t a i n e d by the clothsv a r y i n g with t h e i r c o l o r , is e v i d e n t by some of them h a v i n gsunk a c o n s i d e r a b l e d i s t a n c e i n t o the s n o w , w h i l e o t h e r s r e m a i na p p a r e n t l y unaffected. I t is n e e d l e s s t o add t h a t , in this c a s e ,it was the b l a c k c l o t h s that s a n k the far thes t , the d a r k blue

Fig. 18. Franklin's Pulse Glass.

cloths the n e x t far thes t , a n d then the l i g h t b l u e , w h i l e the p u r e ~w h i t e cloths s c a r c e l y s h o w e d any e f f e c t w h a t e v e r .

(e) H e r e , a g a i n , the utilitarian s ide of the p h i l o s o p h e r a s -s e r t s itself. T h e application of t h e s e f a c t s is evident . B l a c k :c l o t h e s are u n s u i t e d t o w e a r in a hot c l i m a t e ; w h i t e ones~s h o u l d be e m p l o y e d .

Of a s o m e w h a t s i m i l a r character, t h o u g h u n d e r t a k e n s o m etime b e f o r e the e x p e r i m e n t s we have j u s t r e f e r r e d to , areF r a n k l i n ' s e x p e r i m e n t s with a form of a p p a r a t u s that is n o wk n o w n in the p h y s i c a l l a b o r a t o r y as the p u l s e g l a s s . Such ad e v i c e is r e p r e s e n t e d in F ig . 18. This consists of twov e r t i c a l g l a s s , b u l b s , a and b, c o n n e c t e d by m e a n s of ah o r i z o n t a l t u b e of s m a l l d i a m e t e r . T h e a p p a r a t u s is par-tially filled with w a t e r , t h o u g h , in more m o d e r n f o r m s ,p r e f e r a b l y with e t h e r , w h i c h has a m u c h l o w e r b o i l i n gpo in t . W h i l e the u p p e r end of the g l a s s t u b e , b, isVoL. C L X I , No. ~65 23

3 5 4 Houston: [J. F. I.,

s t i l l o p e n , t h e w a t e r in t h e b u l b is v i g o r o u s l y b o i l e d ,s o as t o e x p e l t h e ai r , w h e n t h e t u b e is h e r m e t i c a l l y s e a l e d b yt h e f u s i o n o f t h e g l a s s . B y r e a s o n o f t h e v a c u u m thus p r o -d u c e d i n t h e t u b e , t h e t e m p e r a t u r e o f t h e b o i l i n g p o i n t o f t h el i q u i d is c o n s i d e r a b l y l o w e r e d , s o t h a t t h e heat o f t h e h a n dp l a c e d a t a , as S h o w n in t h e f i g u r e , is suff ic ient t o c a u s e a b r i s kb o i l i n g o f t h e l i q u i d .

I t w o u l d a p p e a r f r o m a l e t t e r w r i t t e n b y F r a n k l i n t o J o h nW i n t h r o p , d a t e d L o n d o n , J u l y 2 , 1 7 6 8 , t h a t F r a n k l i n o b t a i n e da t u b e o f th i s c h a r a c t e r in G e r m a n y , d u r i n g t h e p r e c e d i n g y e a r .F r a n k l i n r e f e r s t o th i s m a t t e r as f o l l o w s :

" I have nothing new in the philosophical way to communicate to you,except what follows. W h e n I was last year in Germany I met with a sin-gular kind of glass, being a tube about e ight inches long, half an inch indiameter, with a hollow ball of near an inch diameter at one end, and oneof an inch and a half at the other, hermetically sealed, and half filed withwater . If one end is held in the hand, and the o t h e r a little elevated abovethe level, a constant succession of large bubbles proceeds from the end inthe hand to the o t h e r end, mak ing an appearance that puzzled me much,tiil I found that the space not filled with water was also free from air, ande i the r filled with a subtle, invisible vapor, continually .x'ising from the water ,and extremely rarefiable by the least heat at one end, and condensableagain by the least coolness at the o t h e r ; o r it is the very fluid of fire itself,which p a r t i n g from the hand pervades the glass, and by its expansive forcedepresses the water till it can pass between the glass and escapes to the o t h e rend, where it gets through the glass again into the air. I am r a t h e r in-clined to the firs t opinion, but doubtful between the two.

"An ingenious ar t i s t here, Mr. Nai rne , mathematical instrument maker ,has made a number of them from mine, and improved t h e m ; for his aremuch more sensible than those I brought from Germany. I bored a verysmall hole through the wainscot in the seat of m y window, through whicha little cold air constantly entered, while the air in the room was keptwarmer by fires made daily in it, being winter time. I placed one of hisglasses, with the elevated end against this hole : and the bubbles fromthe o t h e r end, which was in a warmer situation, were continually pass ing<lay and night, to the no small surprise of even philosophical spectators.Each bubble discharged is larger than that from which it proceeds, and yetthat is not diminished; and by adding itself to the bubble at the o t h e r end,t h a t bubble is not increased, which seems very paradoxical.

" W h e n the balls at each end are made large and the connecting tubevery small, and bent at r igh t angles, so t h a t the balls, instead of being atthe ends, are brought on the side of the tube, and the tube is held so thatthe balls are above it, the water will be depressed in that which is held in thehand, and rise in the o t h e r as a jet o r fountain; when it is all in the other,it begins to boil , as it were, by the v a p o r pass ing up through it; and the

~,~ay, I9o6.] Franklin as aMan of Seienec and an Inventor. 3 5 5

ins t an t i t beg ins t o b o i l , a s u d d e n co ldness is felt i n the ba l l h e l d ; acur ious e x p e r i m e n t t h i s , f irst observed and s h o w n me ~by Mr. Nairne.T h e r e is s o m e t h i n g i n it similar t o the o l d obse rva t ion , I t h i n k , m e n t i o n e db y Ar i s to t l e , that the b o t t o m of a ~boiling p o t i s n o t w a r m ; and p e r h a p s itm a y he lp t o explain that fact, if indeed it be a fact.

" W h e n the w a t e r s t ands at an e q u a l he igh t i n b o t h t h e s e b a l l s , andall at r e s t , if y o u wet one of the ba l l s b y m e a n s of a feather d ipped i n s p i r i t ,t h o u g h that s p i r i t is of the s a m e t e m p e r a m e n t as t o heat and co ld w i t h thew a t e r i n the g la s se s , yet the co ld occas ioned b y the evapora ion o[ thes p i r i t from the w e t t e d b a l l , will s o condense the v a p o r over the w a t e r con-ta ined i n that b a l l , as that the w a t e r of the o t h e r ba l l will be pressed u pip, t o it, fo l lowed b y a success ion of b u b b l e s , till the s p i r i t is a l l d r i e d away.P e r h a p s the obse rva t ions o n t h e s e l i t t l e ins t ruments m a y sugges t and beapp l ied t o s o m e beneficial u s e s . I t has been t h o u g h t , that w a t e r r e d u c e dt o v a p o r b y heat was rarefied o n l y f o u r t e e n thousand t imes, and o n t h i sp r i n c i p l e our e n g i n e s for ra i s ing w a t e r for fire are sa id t o ~e cons t ruc ted ;b u t , if the v a p o r s o much rarefied from w a t e r i s capab le of b e i n g i t s e l f s t i l lf u r t h e r r a r e f i e d t o a bound le s s d e g r e e , b y the app l i ca t ion of heat t o thevesse l s or p a r t s of vesse l s con ta in ing the v a p o r (as at f irst i t i s app l ied t ot h o s e con ta in ing the water), p e r h a p s a much g r e a t e r p o w e r m a y be ob-t a ined , w i t h l i t t l e addi t iona l e x p e n s e . P o s s i b l y , t o o , the p o w e r of eas i lym o v i n g w a t e r from one end t o the o t h e r of a moveable beam (suspendedi n the middle l ike a scale-beam) b y a s m a l l d e g r e e of hea t , m a y be app l iedadvantageous ly t o s o m e o t h e r m e c h a n i c a l purposes ."

F r a n k l i n ' s e x p l a n a t i o n of t l~e p h e n o m e n a of t h e p u l s e g l a s swas , g e n e r a l l y s p e a k i n g , c o r r e c t . H i s m a n n e r o f i n c r e a s i n gt h e d i f f e r e n c e o f t e m p e r a t u r e b e t w e e n t h e t w o b u l b s w a s in -g e n i o u s , t h o u g h s i m p l e ; i . e., b y s u b j e c t i n g t h e s e t w o b u l b s t ot h e t e m p e r a t u r e of t h e o u t e r air , a n d o f a h e a t e d r o o m , r e s p e c t -i v e l y , b y p l a c i n g o n e b u l b n e a r a s m a l l h o l e b o r e d t h r o u g h t h ew a i n s c o t i n a w i n d o w s e a t , t h r o u g h w h i c h a s m a l l q u a n t i t y o fc o l d a i r e n t e r e d , a n d l e a v i n g t h e o t h e r b u l b e x p o s e d t o t h ew a r m a i r of t h e r o o m .

D u r i n g t h e l a t t e r p a r t o f h i s l i f e , F r a n k l i n s u f f e r e d f r o m f a i l -i n g s i g h t . W h e n s e v e n t y - n i n e y e a r s o f a g e , h e r e f e r s t o t h i sm a t t e r , i n a l e t t e r t o G e o r g e W h a t l e y , d a t e d P a s s y , A u g u s t 2 I ,I 7 8 4 , a s f o l l o w s :

" Y o u r eyes must con t inue very g o o d s ince y o u can w r i t e s o s m a l l ahand w i t h o u t spec ta les . I c a n n o t d i s t i n g u i s h a l e t t e r even of l a r g e p r in t ;b u t a m h a p p y i n the inven t i on of d o u b l e spec tac les , wh ich , se rv ing ford i s t an t ob jec t s as wel l as gear o n e s , m a k e my eyes as useful t o me as everthey w e r e . If all the o t h e r defects and infirmities were as eas i ly andcheaply remedied, i t w o u l d be w o r t h w h i l e for fr iends t o l ive a g r e a t deal

356 Houston: [J. F. I.,

longer , but I look upon dea th to be as necessary t o our constitution assleep. We shall r ise refreshed in the morn ing . "

T h e d o u b l e s p e c t a c l e s t o w h i c h he r e f e r s a s h a v i n g i n v e n t e dare w h a t are now g e n e r a l l y c a l l e d bifocals. They w e r e madefor F r a n k l i n u n d e r his direction, in P a r i s , by a F r e n c h optician.F r a n k l i n thus d e s c r i b e s t h e s e spectacles in a l e t t e r t o G e o r g eW h a t l e y , d a t e d P a s s y , M a y 23, I 7 8 5 :

"By Mr. Dollond's say ing t h a t my double spectacles can only serveparticular eyes, I doubt he has not been right ly informed of the i r con-struction. I imagine it will be found pretty generally t rue , t h a t the sameconvexity of glass, through which a man sees clearest and best at the 'dis-t ance l~roper for reading, is not the best for grea te r distances. I t h e r e -fore had formerly two pairs of spectacles, which I shifted occasionally,as in travelling I sometimes read, and often wanted to regard the pros-pects. Finding this change troublesome, and not always sufficiently ready,I had the glasses cut, and half of each kind associated in the same circle,t h u s ~

:Fig . 19. F r a n k l i n ' s DoubleSpecta-cles o r Bifocals.

By this means, as I wear my spectacles constantly, I have only to movem y eyes up o r down, as I want t o see distihctly far o r near , the p r o p e rglasses being always ready. This I find more particularly convenientsince m y being in France; the glasses that serve me best at the table tosee what I eat, not being the best to see the faces of those o n the o t h e r sideof the ta~)le who speak to me; and when one 's ears are not well accus-t o m e d t o the sound of a language, a s ight of the movements in the featuresof him t h a t speaks, helps to explain; (a ) so that I unders tand Frenchbetter by the help of my spectacles."

(a) By this w i t t y r e m a r k , F r a n k l i n of c o u r s e r e f e r s t o the factthat he made up, by the use of his e y e s , for w h a t his ears l a c k e din t h o r o u g h l y a p p r e c i a t i n g the s o u n d s of a l a n g u a g e t o w h i c hhe was not a c c u s t o m e d .

W h i l e in L o n d o n , on one of his many visits t o E n g l a n d ,F r a n k l i n s a w a m u s i c a l i n s t r u m e n t c a l l e d a n a r m o n i c a . Thisi n s t r u m e n t consists of g l a s s v e s s e l s of v a r y i n g s i z e s , w h i c hw h e n r u b b e d by p a s s i n g the m o i s t e n e d f i n g e r a r o u n d t h e i rr i m s , e m i t s the n o t e s of the m u s i c a l s c a l e o r g a m u t . B e i n gm u c h p l e a s e d with the s w e e t n e s s of i t s n o t e s , F r a n k l i n g r e a t l y

May, I9O6.] Franklin as aMan of Scienec and an Inventor. 357

i m p r o v e d the instrument, so as t o i n c r e a s e the n u m b e r of t o n e sit was c a p a b l e of p r o d u c i n g , while, a t the same t i m e , p l a c i n git in a m u c h s m a l l e r space.

In F r a n k l i n ' s i m p r o v e d form of a r m o n i c a , the differentg l a s s e s were m a d e in the form of hemispheres, p r o v i d e d wi th anopen neck and a s o c k e t in the m i d d l e for f i x i n g them t o an ironspindle. The spindle, h o l d i n g the glasses, w a s p l a c e d h o r i -zontally a n d m o v e d by a t r e a d l e in a m a n n e r s i m i l a r t o t h a t ofthe spinning wheel. The p e r f o r m e r sat in f r o n t of the instru-m e n t a n d b r o u g h t out the r e q u i r e d t o n e s by p l a c i n g them o i s t e n e d f i n g e r s on the rims of the r o t a t i n g glass.

F r a n k l i n d e s c r i b e s his i m p r o v e d i n s t r u m e n t in a l e t t e r wr i t -ten t o the Rev. J o h n Bapt is t B e c e a r i a , d a t e d L o n d o n , July 13,1762 :

"I once promised myself the pleasure of seeing you at Turin; but asthat is not now likely to happen, being just about returning to my nativecountry, America, I sit down to take leave of you (among other of myEuropean friends that I cannot see) by writing.

"I thank you for the honorable mention you have so frequently madeof me in your letters to Mr. Collinson and others, for the generous de-fence you undertook and executed with so much success, of my electricalopinions; and for the valuable present you have made me of your newwork, from which I have received great information and pleasure. I wishI could in return entertain you with anything new of mine on that subject;but I have not lately pursued it. Nor do I know of any one here, thatis at present much engaged" in it.

"Perhaps, however, it may be agreeable to you, as you live in a mu-sical country, to have an account of the new instrument lately added hereto the great number that charming science was before possessed of. Asit is an instrument that seems peculiarly adapted to Italian music, especi-ally that of the soft and plaintive kind, I will endeavour to give you adescription of it, and of the manner of constructing it, that you or any ofyour friends may be able to imitate it, if you incline to do so, withoutbeing at the expense add trouble of the many experiments I have madei t : endeavouring to bring it to its present perfection.

"You have doubtless heard the sweet tone that is drawn from a drink-ing-glass by passing a wet finger around its brim. One Mr. Puckeridge,a gentleman from Ireland, was the first who thought of playing tunes,formed of these tones. He coIlected a number of glasses of different sizes,fixed them near each other on a table, and tuned them by putting intothem water more or less, as each note required. The tones were broughtout by passing his fingers round their brims. H e was unfortunatelyburned here, with his instrument, in a fire which consumed the house helived in. Mr. E. Delaval, a most ingenious member of our Royal Society,

3 5 8 H o u s t o n : []. F. I.,

made one in imitation of it, with a be t t e r choice and form of glasses, whichwas the first I saw o r heard. Being charmed by the sweetness of its tones ,and the music he produced from it, I wished only to see the glasses dis-posed in a more convenient form, and brought toge the r in a narrowercompass, so as to admit of a grea te r number of tones , and all within reachof h a n d to a person sitting in front of the instrument, which I accom-plished, after various intermediate t r ia ls and less commodious forms, bothof glasses and construction in the following manner :

"The glasses are 'blown as near as possible in the form of hemispheres,having each an open neck o r socket in the middle. (Fig. 2o.)The thickness of the glass near the brim about a tenth of an 'inch,o r hardly qui te so much, but th i cke r as it comes neare r the neck,which in the largest glasses is about an inch deep, and an inch and a halfwide within, these dimensions lessening, as the glasses themselves dimin-ish in size, except that the neck of the smallest ought not to be sho r t e rthan half an inch. The largest glass is n~neinches diameter, and thesmallest t h r e e inches. Between these two are twenty-three different sizes, dif-fering from each o t h e r a quar ter of an inch in diameter. T o make a single

Fig. 20instrument t h e r e should be at least six glasses blown of each size; and outof this number one may probably pick thirty-seven glasses (which are suffi-cient for t h r e e octaves with all the semi-tones) that will fbe each either thenote one wants o r a little sharper than that note, and all fitting so wellinto each o t h e r as to t a p e r pretty regularly from the largest to the smallest.I-? is true that t h e r e are not thirty-seven sizes, but it often happens that twoof the same size differ a note or half note in tone, by reason of a differ-ence in thickness, and these may be placed one in the o t h e r without sen-sibly hur t ing the regularity of the t a p e r form.

"The glasses being chosen and every one marked with a diamondthe note you intend for it, they are to be tuned by diminishing the thick-ness of those that are too sharp. This is done by grinding them roundfrom the neck towards the brim, the breadth of one o r two inches, as maybe required; often t r y i n g the glass by a well-tuned harpischord, com-paring the tone drawn from the glass by your finger, with the note youwant, as sounded by that s t r ing of the harpischord. When you comeneare r the matter, be careful to wipe the glass c lean and dry before eachtrial, because the tone is somewhat flatter when the glass is wet, than itwill he when dry; and, gr inding a very little between each trial, you willthereby tune to great exactness. The more care is necessary in this , be-

May, I9o6.] Franklin as aMan of Scienec and an Inventor. 3 5 9

cause, if you go below your required tone, t h e r e is n o sharpening it againbut by grinding somewhat off t h e brim, which will a~terwards requirepolishing, and thus increase the trouble.

"The glasses being thus tuned, you are t o be provided with a casefor them, and a spindle o n which they are to be fixed. (Fig. 21.)My case is about t h r e e feet long, eleven inches eve ry way widewithin at the biggest end, and five inches at the smallest end; forit tap.ers all the way, t o adapt it be t t e r to the conical figure of theset of glasses. This case opens in the middle of its height, and the upper

Fig. 21.

part t u r n s up by hinges fixed behind. The spindle, which is of hard i ron ,lies horizontally from end to end of the box within, exact ly in the middle,and is made to turn on brass gudgeons at each end. I t is round, an inchdiameter at the thickest end, and tapering to a quar ter of an inch at thesmallest. A square shank comes from its thickest end through the box,on which shank a wheel is fixed by a screw. This wheel serves as a fly tomake the motion equable, when the spindle, with the glasses, is tu rned bythe foot like a spinning wheel. My wheel is of mahogany, e ighteen inchesdiameter, and pretty thick, so as to conceal near its circumference abouttwenty-five pounds of lead. An ivory pin is fixed o n the face of this wheel,and about four inches from the axis. Over the neck of this pin is put theloop of the string that comes up from the movable step to give it motion.The case stands on a neat f rame with four legs.

3 6 0 Houston: [J. F. I.,

"To fix the glasses on the spindle, a cork is f irs t to be fitted in eachneck pretty tight, and projecting a little without the neck, that the neckof one may not touch the inside of another when put together, for thatwould make a jarring. These corks are t o be perforated with holes ofdifferent diameters , so as t o suit that part of the spindle on which they areto, he fixed. W h e n a glass is l~ut .on, by hold ing it stiffly between bothbands, while a n o t h e r t u r n s the spindle, it may be gradually brought to itsplace. But care must be t a k e n that the hole is not too small , lest, inforcing it up, the neck should be split; n o r too large, lest the glass, notbeing firmly fixed, should tu rn or move o n the spindle, so as to touchand jar against its neighbor ing glass. The glasses are thus placed one inanother, the largest on the biggest end of the spindle, which is to the lefthand; the neck of this glass is towards the wheel, and the next goes intoit in the same position, only about an inch of its brim appearing beyondthe brim of the first; thus proceeding, every glass when fixed, shows aboutan inch of its brim (or three-quarters of an inch, o r half an inch, as theygrow smaller) beyond the brim of the glass that contains it; and it is fromthese exposed parts of each glass t h a t the tone is drawn, by laying a f ingerupon one of them as the spindle and glasses turn round.

" M y largest glass is G, a little below the reach of a common voice,and my highest G, including t h r e e complete octaves. T o distinguish theglasses the more readily to the eye, I have painted the apparent part ofthe glasses within side, every semi-tone, white, and the o t h e r no t e s of theoctave with the seven prismatic colors, viz: C, red; D, orange; E, yellow;F, green ; G, blue; A, indigo; B, purple; and C, red again ; so that glassesof the same co lor (the whi t e excepted) are always octaves to each other.

" T h i s instrument is played upon by sitting before the middle of the setof glasses as before the keys of a harpischord, tu rn ing them with the footand wet t ing them now and then with a sponge and clean water. Thefingers should be first a little soaked in water , and qui te free from allgreasiness; a little fine chalk upon them is somet imes useful, tomake them catch the glass and br ing out the tone more readily. Bothhands are used, by which m e a n s different parts are played together. Ob-serve, that the tones are best drawn out when the glasses turn from theends of the fingers, and not when they turn to them.

"The advantages of this instrument are, that its t ones are incompar-ably sweet, beyond those of any o t h e r ; that they may be swelled andsoftened at pleasure by s t ronger o r weaker pressure of the finger, andcontinued to any leng th ; and that the instrument, being once well tuned,neve r again wants tuning.

"In h o n o r of your musical language, I have borrowed from it the nameof this instrument, calling it the Armonica.

" W i t h great es teem and respect, I am, &c., B. Franklin."

F r a n k l i n g i v e s t h e f o l l o w i n g di rec t ions as t o t h e best m a n n e ro f o b t a i n i n g t h e s w e e t n o t e s th i s i n s t r u m e n t is c a p a b l e o f p r o -

d u c i n g :

May, I9o6.] Franklin as aMan of Scienec and an Inventor. 3 6 t

"Before you sit down to play, the fingers should be well washed with~oap and water , and the soap well r insed off.

"The glasses must always be kept perfectly clean from the least greasi-ness; therefore suffer nobody to touch them with unwashed hands, foreven the common, slight, natural greasiness of the skin rubbed o n themwill prevent t he i r sounding for a long time.

"You must be provided with a little bo t t l e of rain water , (spring wateri~ generally too hard, and produces a harsh tone,) and a middling sponge

Fig. 22. F r a n k l i n ' s I m p r o v e m e n t on t h e A r m o u i c a .

in a little slop-bowl, in which you must ke.ep so much of the water that thesponge may always be very wet.

" I n a teacup keep also ready some fine scraped chalk, free from grit,t o be used on occasion.

"The fingers when you begin to play should not only be wet on the.~urface, but the skin a little soaked, which is readily done by press ing themhard a few t imes in the sponge.

"The first t h i n g after setting the glasses in motion is to pass the sponge.slowly along from the biggest glass t o the smallest, suffering it to rest on

362 Houston: [J. F. I.~

each glass during at least one revolution of the glasses, whereby they willall be made moderate ly wet. If too much water is left o n them, they willnot sound so readily.

"If the instrument is left near a window, let the window be shut o rthe curtain drawn, as wind or sunshine on the glasses dries them too fast.

" W h e n these particulars are all attended to, and the directions ob-served, the tone comes forth finely with the sl ightest pressure of the finger~imaginable, and you swell it at pleasure by adding a little more pressure,no instrument affording more shades, if one may so speak, of the F o r t epiano.

"One wet t ing with the sponge will serve for a piece of musictwice a~long as Handel 's Water-piece, unless the air be uncommonly drying.

"But a number of thin slices of sponge, placed side by side, t he i rends held fast between two strips of wood, like rulers, of a leng th equal t othe glasses, and placed so that the loose ends of the sponges may touch t h eglasses behind, and by that m e a n s keep them constantly wet, is very con-venient where one purposes to play for a long time. The sponges beingproperly wet ted will supply the glasses sufficiently a whole evening, andtouching the glasses l ightly do not in the least hurt the sound.

"The powder of chalk is useful two ways."Fingers, a f t e r much playing, sometimes begin to draw out a t o n e

less smooth and soft, and y o u feel as well as hear a small degree of sharp-ness. I n this case, if you dip the ends of your wet fingers in the chalk~it will immediately recover the smoothness of tone desired. And, if t h eglasses have been sullied by handling, or the fingers not being just washedhave some little greasiness on them, chalk so used will c lean both glasse9and fingers, and the sounds will come out to your wish.

"A little practice will make all this familiar; and you will also tinctby t r ia ls what par t of the fingers most readily produces the sound fromparticular glasses, and whether they require to be touched on the edgechiefly, or a little more on the side; as different glasses require a differenttouch, some pretty full on the flat side of the brim, to br ing out the besttone, others more on the edge, and some of the largest may need the touchof two fingers at once."

Fig . 22 r e p r e s e n t s a p h o t o g r a p h of an a r m o n i c a , c o n s t r u c t e dby F r a n k l i n . A s will be s e e n , it differs in no r e s p e c t from theone r e p r e s e n t e d in F i g s , 20 and 21, save in s o m e u n i m p o r t -ant d e t a i l s . T h e p o s i t i o n of the m u s i c i a n o p e r a t i n g this in-strument , h o w e v e r , is c l e a r l y s h o w n in the p h o t o g r a p h . *

Pitt Rivers Museum, University of Oxford, Sep. 9, I9o4.DEAR DR. GOLDSCMIDT:

T h a n k you very much for having so kindly sent me the photograph

*'As will be seen from the accompanying letter, da ted Sep. 27, I9O4~from Prof. Henry Balfour, of the University of Oxford, transmitted by Dr .V. Goldsmidt, the construction is the same as tt~at already given a~bc~ve.

May, 19o6.] Franklin as aMan of Science and an Inventor. 3 6 3

which is very interesting to me. The instrument represented is not a str ing-ed instrument but a "Glasharmonica" and consists of 2o o r more hemi-spherical glass bowls all fixed upon a long rod or spindle, which passesthrough the centres. One end of the spindles is attached to a wheel, whichcan be rotated by m e a n s of a pedal o r foot board. W h e n the wheel is setrevolving (by pedalling with the foot) all the glasses revolve toge the r andas they are carefully graduated in size (the base o n the cleft and treble on theright) scales can be p layed o r even chords and harmonics. The pe r fo rmerwe1s his fingers and re s t s them upon the revolving glasses; the friction causingthem t o vibrate and emit t he i r respective notes . Your picture illustratesthe mcthod of playing excellently. I enclose a r o u g h sketch of the instru-ment from the base end to show the wheel and treadle and also one toshow how the bowls are fixed onto the spindle, overlapping so as to br ingthem all as close toge the r as possible to al low of harmonics and chords be-ing played. This form of the instrument was invented by the celebratedAmerican, Benjamin Franklin, about the year I76o, and was an improvementupon the earlier musical glasses upon which the celebrated composer Glueckused to perform.

I have seen very few examples of the "Glasharmonica." T h e r e is one inthe South Kensington Museum in London and I have seen two o r threeo t h e r examples. You are fortunate to have this picture, which from thecostume would seem t o date from x78oqSoo. Can you tell me, if it is da tedexactly and whom it represents in the act of playing? I assume that thepicture is German.

Thanking you again for the photograph and with kindest regards.Yours very truly,

HENRY BALFOUR.

F r a n k l i n c o r r e c t l y a s c r i b e s t h e p h e n o m e n a o f S t . E l m o ' s f i re ,o r a s t h e y are g e n e r a l l y c a l l e d b y s a i l o r s , c o r p o s a n t s o rc o m a z a n t s , t o e lec t r ica l p o i n t d i s c h a r g e s . H e thus r e f e r s t ot h e s e p h e n o m e n a i n a l e t t e r t o Col l inson, d a t e d J u l y 2 7 , I75O:

"June 29, I751. I n Capt. Waddell 's account of the effects of lightning o nhis ship, I could not but take notice of the large comazants (as he callsthem) that settled on the spintles at the top-mas t beads, and burnt like verylarge torches (before the stroke). According. to my opinion, the electricalfire was then drawing off, as by points, from the cloud; the l~rgeness of theflame betokening the great quantity of electricity in the cloud: and hadt h e r e been a good wire communication from the spindle heads to the sea,that could have conducted more freely than t a r r e d ropes, ~,r m a s t s of tur-pentine wood, I imagine t h e r e would either have been no s t roke ; or, if astroke, the wire would have conducted it all into the sea without damage tothe ship."

I t will be r e m e m b e r e d t h a t w h i l e d i s c u s s i n g t h e F r a n k l i n l e t -t e r , in w h i c h he d e s c r i b e s t h e cons t ruc t ion o f his m o v a b l e e l e c -

364 Houston: [J. F. I.,

tric c louds ; i. e., the cloud consis t ing of a movable pasteboardtube o r of a charged scale pan of a balance, reference was madeto the fact tha t F r a n k l i n had conceived an erroneous idea con-cerning what he called cold fusion, the reference to which wasdeferred to another part of the article. This we were also themore willing to do, from the fact tha t this article contained ref-erence to important m a t t e r s of a different character.

I t w o u l d appear that Franklin was led to this change of opin-ion concerning the cold fusion of m e t a l s as follows: Hisfriend Kinnersley, of London, had sen t to F r a n k l i n a let ter de-scribing a form of electrical thermometer he had devised. This

P

L

IFig . 47. P a g e d 17, Vo l . 1. E l e c -

t r i c i t y I n E v e r y - d a y L i f e .Our Fig'. 23.

form of thermometer consisted as represented in Fig. 23 , of twoglass s t u b s of unequal diameter, communicating with eachother at their .lower ends by means o f a horizontal tube. A me-~:allic cap closes the upper end of the larger tube. Throughthis cap a metallic rod extends, terminating at bo th of its endsin smooth metallic balls, the opening being of such dimensionthat the rod can be slid up and down with some little friction.Another metallic ball is a t tached to the upper end of a metal-lic rod, permanently f i x e d in the lower part of the en-closed tube as shown. The sliding rod is so placed as toleave a small air gap between it and the lower end of the ball

May, i9o6.] Franklin as aMan of Scienec and an Inventor. 365

c o n n e c t e d wi th the f i x e d rod. As will be s e e n , the s m a l l e r tubeis left open at the top. Sufficient w a t e r is p l a c e d in the tubet o b r i n g the l e v e l of the l i q u i d b e l o w the top of the l o w e r f i x e dball. W h e n , now, a disruptive d i s c h a r g e is p a s s e d b e t w e e n thetwo b a l l s in the e n c l o s e d t u b e , by the d i s c h a r g e of a L e y d e n jar,the h e a t p r o d u c e d c a u s e s an e x p a n s i o n of the c o n t a i n e dair, and so depresses the c o l u m n of w a t e r in the e n c l o s e dt u b e , r i s i n g the level in the open t u b e . With powerfuldischarges, the w a t e r m a y even be violently t h r o w n o u tfrom the top of the s m a l l e r t u b e , a part of this m o v e m e n t b e i n gd u e t o the s u d d e n blow o r m o t i o n g i v e n t o the air by the dis-c h a r g e . T h a t , h o w e v e r , the depression of the c o l u m n is alsodue t o the increase in the t e m p e r a t u r e of the air c o n s e q u e n t onthe p a s s a g e of the d i s c h a r g e , is seen by the fact that the w a t e ris m a i n t a i n e d a t a h i g h e r l e v e l in the open tube u n t i l the air inthe e n c l o s e d tube has r e a c h e d i ts f o r m e r t e m p e r a t u r e .

I n the same l e t t e r , K i n n e r s l e y d e s c r i b e s a n o t h e r e x p e r i m e n tw h i c h h e made in a c c o r d a n c e wi th a s u g g e s t i o n of F r a n k l i n ,that also r e f e r s t o w h a t F r a n k l i n c a l l s cold fusion. K i n n e r s -ley's description of this e x p e r i m e n t is as follows:

"I then suspended, out of the thermometer, a piece of small harpis-chord wire, about twenty-four inches long, with a pound weight at thelower end, and sent the charge of the case of five and thirty bottlesthrough it, whereby, (a) I discovered a new method of wire-drawing. Thewire was red-hot the whole length, well annealed, and above an inch longerthan before. A second charge melted it; it parted near the middle, andmeasured, when the ends were put together, four inches longer than atfirst. This experiment, I remember, you proposed to me before you leftPhiladelphia; but I never tried it till now. That I might have no doubtof the wire's being hot as well as red, I repeated the experiment on an-other piece of the same wire, encompassed with a goose-quill, filled withloose grains of gunpowder; which took fire as readily as if it had beentouched with a red-hot poker. Also tinder, tied to another piece of thewire, kindled by it. I tried a wire about three times as big, but could pro-duce no such effects as that.

"Hence it appears that the electric fire, though it has no sensible heatwhen in a state of rest, will, by its violent motion, and the resistance itmeets with, produce heat in other bodies when passing through them,provided they be small enough. A large quantity will pass through a largewire without producing any sensible heat; when the same quantity, passingthrough a very small one, being more confined to a narrower passage, theparticles crowding closer together and meeting with greater resistance,will make it red-hot, and even melt it.

3 6 6 Houston: [L F. I.,

" H e n c e l i g h t n i n g does n o t melt m e t a l b y a co ld fus ion , as we formerl]'svpposed ; b u t when i t passes t h r o u g h the b l a d e of a sword , if the quan t i t yhe n o t very grea t , it m a y heat the p o i n t s o as t o melt it, w h i l e the broades tand th ickes t part m a y n o t be sens ib ly w a r m e r than b e f o r e .

" A n d , when t r e e s o r h o u s e s are set o n fire b y the dreadful quan t i t yw h i c h a c l o u d , or the ear th , s o m e t i m e s d ischarges , m u s t . n o t the heat b yw h i c h the wood i s first k i n d l e d , be generated b y the l i g h t n i n g ' s v io l en tm o t i o n t h r o u g h the re s i s t i ng combus t ib le m a t t e r ? "

( a ) " I d i s c o v e r e d a n e w m e t h o d o f w i r e - d r a w i n g . " H e r e w eh a v e a g o o d d e s c r i p t i o n o f a m e t h o d f o r e l e c t r i c a l l y d r a w -i n g a n d a n n e a l i n g w i r e , m a d e a t a t i m e w h e n t h e v o l t a i ch e a t e d t h e s t e e l w i r e t o s u c h a n e x t e n t a s t o p e r m i t i t t o b ed r a w n o u t , a n d , o n t h e p a s s a g e o f a s e c o n d d i s c h a r g e , t o b ed r a w n o u t s t i l l f u r t h e r ( a t t h i s t i m e t h e w i r e b r e a k i n g ) , t h ee l o n g a t i o n p r o d u c e d b y t h e t w o d i s c h a r g e s m e a s u r i n g a b o u tf o u r i n c h e s . A t t h e s a m e t i m e , t h e w i r e w a s a n n e a l e d b y r e a -s o n o f t h e g r a d u a l c o o l i n g t o w h i c h i t w a s e x p o s e d . T h i s e x -p e r i m e n t w a s , a s K i n n e r s l e y a c k n o w l e d g e d , s u g g e s t e d b yF r a n k l i n .

F r a n k l i n ' s r e p l y t o t h i s l e t t e r o f K i n n e r s l e y w a s d a t e d L o n -d o n , F e b r u a r y 2 o t h , 1 7 6 2 , a n d w a s a s f o l l o . w s :

(a) "I a m much pleased w i t h your electrical thel"mometer, and the experi -m e n t s y o u have m a d e w i t h it. I f o r m e r l y sat is f ied m y s e l f , b y an experi -ment w i t h m y phial and s i p h o n , that the e las t i c i ty of the a i r was n o t in -c r e a s e d b y the m e r e existence of an e lec t r i c a t m o s p h e r e w i t h i n the ph i a l ;b u t I d i d n o t k n o w , till y o u now i n f o r m me, that heat m a y be g iven t o i tb y an e lec t r i c exp los ion . The cont inuance of its rarefact ion, for s o m etime a f t e r the discharge of your g l a s s jar and your case of b o t t l e s , s e e m s:to m a k e t h i s clear. The o t h e r experiments o n wet p a p e r , w e t th read ,g r e e n grass , and g r e e n w o o d , are n o t s o sat is fac tory; as p o s s i b l y the re-duc ing part of the moisture t o v a p o r , b y the e lec t r i c f luid pas s ing t h r o u g hit, m i g h t occas ion s o m e expansion w h i c h w o u l d be gradua l ly r e d u c e d b ythe condensa t ion of such vapor . T h e fine s i lve r th read , the very s m a l lbrass wire, and the s t r i p of g i l t p a p e r , are a l so subject t o a similar objec-t i o n , as even metals , i n such circumstances, are o f t e n par t ly r e d u c e d t os m o k e , par t icu la r ly the g i l d i n g o n p a p e r .

(b) "But your subsequen t beaut i ful e x p e r i m e n t o n the w i r e , w h i c h y o u•made h o t o y the e lec t r t c exo los ion , and i n that s t a t e f i r e d gunpowderw i t h it, p u t s i t o u t of a l l q u e s t i o n , that heat is produced b y our artificial

e lec t r i c i ty , and t h a t . t h e m e l t i n g of m e t a l s i n that way , is n o t what I for-m e r l y cal led a co ld fus ion . A l a t e ins tance here of the m e l t i n g of the b e l l -w i r e , i n a h o u s e s t r u c k b y l i g h t n i n g , and p a r t s of the wire burn ing h o l e si n the f l o o r o n w h i c h they fel l , has p r o v e d the s a m e w i t h r e g a r d t o the elec-t r i c i ty of nature. I was t o o eas i ly led i n t o t h a t e r r o r b y accounts g iven

~{ay, 19o6.] F r a n k l i n a s a M a n o f S c i e n e c a n d a n Inven tor . 3 6 7

even in philosophical books, and from r e m o t e ages downwards, of melt-ing m o n e y in purses, swords in scabbards, &c., without burning the in-flammable matters that were so near those melted metals. But men are,in general, such careless observers, that a philosopher cannot be too muchon his guard in crediting the i r relations of th ings extraordinary, andshould neve r build any hypothesis on anything ~but clear facts and experi-ments, o r it will be in danger of soon falling, as this does, like a house ofcards.

(c) "How many ways there are of kindling fire, or producing heat inbodies! By the sun's rays, by collision, by friction, by hammering, by pu t re -faction, by fermentation, q~y mixtures of solids with fluids, and by electricity.And yet the fire when produced, though in different bodies it may differ in cir-cumstances, as in color, vehemence, &c., yet in the same bodies is gener-ally the same. Does not this seem t o indicate that the fire existed in thebody, though in a quiescent state, before it was by any of these means ex-cited, disengaged, and brought forth to action and t o view? May it notconstitute a part, and even a principal part, of the solid substance of bodies?I[ this should be the case, kindling a fire in a body would be nothing morethan developing this inflammable principle, and setting it at liberty to act~,l separating the parts of that body, which then exhibits the appearanceso f scorching, melting, burning, &c. When a man lights a hundred candlesfrom the flame of one, without diminishing that flame, can it be properlysaid t o have communicatezt all that fire? W h e n a single spark from a flintapplied to a magazine of gunpowder, is immediately attended with thisconsequence, that the whole is in flame, exploding with immense violence,could all this fire exist f i rs t in the spark? We cannot conceive it. Andthus we seem led to this supposition, that t h e r e is fire enough in all bodiesto singe, melt, o r burn them, whenever it is, by any means, set at liberty,so that it may exer t itself upon them, o r be disengaged from them. Thisliberty seems t o be afforded it by the passage of electricity through them,which we know can. and does, of itself, separate the par ts , even of water ;and, perhaps , the immediate appearances of fire are only the effects of suchseparations. If so, t h e r e would be n o need of supposing that the electricfluid hea t s i t s e l f by the swiftness of its motion, or heats bodies by the re -sistance it meets with in pass ing through t h e m . They would only be heatedin proportion as such separation could be more easily made. Thus a melt-ing heat cannot be given to a large wire in the flame of a candle, though itmay to a small one; and this , not because the large wire resists less thatac t i on of the flame which tends to separate its parts, but because it res i s t sit more than the smaller wire, o r because the force being divided betweenIno re parts acts weaker on each."

(a ) F r a n k l i n at once a c k n o w l e d g e s t h a t t h e c o n t i n u e d d e p r e s -s ion o f t h e w a t e r in t h e e n c l o s e d v e s s e l u n q u e s t i o n a b l y i n d i -c a t e s arL i n c r e a s e o f t e m p e r a t u r e c a u s e d b y t h e p a s s a g e o f t h ed i s c h a r g e t h r o u g h t h e ai r , and t h a t , t he r e fo re , t h e e x p e r i m e n t

368 Houston: [J. F. I.,

p r o v e s that electr ici ty is c a p a b l e of p r o d u c i n g h e a t in b o d i e sj u s t like o r d i n a r y hea t .

• ( b ) T h e f u s i o n of the m e t a l l i c w i r e a n d the s u b s e q u e n t i g n i t i o nof the g u n p o w d e r show b e y o n d q u e s t i o n that electr ici ty pro-d u c e s h e a t , so that F r a n k l i n a c k n o w l e d g e s that his f o r m e r con-c e p t i o n of the cold f u s i o n of m e t a l s m u s t be a b a n d o n e d a s er-r o n e o u s . H e then c o m p a r e s this r e s u l t with the case of a l i g h t -ning s t r o k e r e c e n t l y b r o u g h t t o his a t t e n t i o n w h i l e in L o n d o n ,in w h i c h the bolt m e l t s a bell w i r e , the f u s e d g l o b u l e s d r o p p i n gfrom w h i c h b u r n t h o l e s in the f l o o r of the r o o m on w h i c h theyfell.

I have i n c l u d e d this p a r a g r a p h a s i n t e r e s t i n g in s h o w i n g thec u r i o u s i d e a s F r a n k l i n h a d a t this t ime r e s p e c t i n g the c a u s e sof hea t .

(c) W e find a m o n g F r a n k l i n ' s w r i t i n g s on w h a t m a y p r o p e r l ybe r e g a r d e d as theoretical p h y s i c s , a c o m p a r a t i v e l y s h o r t p a p e rc o n c e r n i n g the o r i g i n of l ight . It will be seen from this p a p e rthat h e was a d i s b e l i e v e r in the N e w t o n i a n o r c o r p u s c u l a rt h e o r y of l i g h t ; i. e., that l i g h t is due t o e x c e e d i n g l y m i n u t ec o r p u s c l e s shot off with a l m o s t inconceivable r a p i d i t y from thes u r f a c e of the sun, b e i n g d i s p o s e d t o a c c e p t the H u y g h e n i a nt h e o r y , that l i g h t is p r o d u c e d by u n d u l a t i o n s or v i b r a t i o n s in a ne x c e e d i n g l y t e n u o u s m e d i u m that fills all s p a c e . This may beseen from the f o l l o w i n g q u o t a t i o n , t a k e n from a l e t t e r w r i t t e nby F r a n k l i n , d a t e d A p r i l 23, I 7 5 2 :

"I t h a n k you for communicating the illustration of the t h e o r e m con-cerning light. I t is very curious. But I must own "I am much in the darkabout light. ( a ) I am not satisfied with the doctrine that supposes par-ticles of m a t t e r called light, continually dr iven off from the sun's surface,with a swiftness so prodigious! Must not the smallest particle conceivable,have with such a motion, a force exceeding that of a twenty-four pounder , dis-charged from a cannon? Must not the sun diminish exceedingly by such awaste of matter; and the planets, instead of drawing near to him, as somehave feared, recede t o grea te r dis tances through the lessened attraction.Yet these particles, with this amazing motion, will not drive before them,or remove, the least and lightest dust they meet wi th : And the sun, foraught we know, continues of his ancient dimensions, and his attendantsmove in the i r ancient orbits .

( b ) "May not all the phenomena of l ight be more conveniently solved,by supposing universal space filled with a subtle elastic fluid, which, whenat rest, is not visible, but whose vibrations affect that fine sense of theeye, as those of air do those the grosser o rgans of the ear? We do not,

~'[ay, I9o6.] Frankli~ as aMan of Scicnec and alz Inz,entor. 3 6 9

i n the case of s o u n d , i m a g i n e that any sonorous part ic les are t h r o w n offfrom a b e l l , for ins tance , and fly i n s t r a i t l ines t o the ear; why must webel ieve that luminous part ic les l e a v e the s u n and p r o c e e d t o the eye? S o m ediamonds , if rubbed , sh ine i n the dark , w i t h o u t l o s i n g any part of t h e i rm a t t e r . I can make an electrical s p a r k as b i g as the f l a m e of a candle,much br ighter , and , therefore, v i s i b l e f u r t h e r ; yet t h i s is w i t h o u t fuel; and ,I a m persuaded , n o part of the e lec t r i c f luid flies off i n such case, t o d i s t an tp laces , b u t all goes d i rec t ly , and i s t o be f o u n d i n the p l a c e t o w h i c h I des-t ine it. May n o t different d e g r e e s of the v ib ra t ion of the a b o v e - m e n -t ioned universal m e d i u m , occas ion the appearance of different co lou r s? It h i n k the e lec t r i c f luid i s a lways the s a m e ; yet I find that w e a k e r ands t ronger s p a r k s d i f f e r i n apparent colour , s o m e whi te , b lue , purple , red;the s t ronges t , w h i t e ; weak o n e s , red . Thus different d e g r e e s of v ib ra t iong iven t o the a i r p r o d u c e the s e v e n different s o u n d s i n music, ana logous t othe Seven co lou r s , yet the m e d i u m , air , i s the s a m e . '

( a ) F r a n k l i n r e f e r s t o t h e t r e m e n d o u s p o w e r t h a t t h es m a l l e s t c o n c e i v a b l e p a r t i c l e o f m a t t e r w o u l d h a v e i f i t w e r es h o t o f f f r o m t h e s u r f a c e o f t h e s u n w i t h t h e v e l o c i t y o f l i g h t .T h i s h e a g r e e s w i t h o t h e r s i n r e g a r d i n g a s a m o s t s e r i -o u s o b j e c t i o n t o t h e c o r p u s c u l a r t h e o r y o f l i g h t . I n s t e a d o fl i g h t p o s s e s s i n g t h e p o w e r o f d e m o l i s h i n g a l l m a t t e r o n w h i d hi t f a l l s , i t i s u n a b l e t o m o v e e v e n t h e l i g h t e s t d u s t p a r t i c l e t h a ti t f a l l s o n .

(b) F r a n k l i n s i m p l y s t a t e s h e r e t h e w e l l k n o w n H u y g n e n i a n o ru n d u l a t o r y t h e o r y o f l i g h t .

A n o t h e r q u e s t i o n t h a t m a y p r o p e r l y b e r e g a r d e d a s b e l o n g - -i n g t o t h e o r e t i c a l p h y s i c s i s a b e l i e f m e n t i o n e d b y F r a n k l i r ~ ,c o n c e r n i n g a c t i o n a t a d i s t a n c e . L i k e m a n y o t h e r p h i l o s o -p h e r s , F r a n k l i n r e j e c t e d t h e p r o b a b i l i t y o f a c t i o n a t a d i s t a n c e ~t h u s w r i t i n g c o n c e r n i n g t h i s m a t t e r i n a l e t t e r w h i c h w a s a f t e r - -w a r d s r e a d a t t h e R o y a l S o c i e t y , N o v e m b e r 4 t h , I 7 5 6 :

"I a g r e e w i t h y o u , that it s e e m s absurd t o s u p p o s e that a b o d y canact w h e r e i t i s n o t . I have n o idea of b o d i e s at a d is tance a t t rac t ing orrepe l l ing one a n o t h e r w i t h o u t the ass i s tance of s o m e m e d i u m , t h o u g h Iknow n o t what that m e d i u m is, or how i t opera tes . When I s p e a k of a t -t rac t ion or r epu l s ion , I m a k e u s e of t h o s e w o r d s for want of o t h e r s m o r eproper , and in t end o n l y t o e x p r e s s o n l y effects which I see, and n o t c a u s e sof w h i c h I a m ignoran t . W h e n I p r e s s a b l o w n bladder between my knees ,I f ind I c a n n o t b r i n g its s ides together , b u t my k n e e s feel a sp r ingym a t t e r , p u s h i n g them back t o a g r e a t e r dis tance , or repe l l ing t h e m . Iconclude that the a i r i t con ta ins i s the cause. And when I opera te o n the a i rand find I cannot by pressure f o r c e i t s part ic les i n t o con tac t , b u t they s t i l lsp r ing back aga ins t the pressure, I conceive that t h e r e must be s o m e m e -VoL. C L X I , N o . 965 24

37 ° Houston: [J. F. I.,

dium between its particles that prevents the i r closing, though I c a n n o t tellwhat it i s . - -And if I were ae-quainted with t h a t medium, and found itsparticles to approach and recede from each other, according to the pressurethey suffered, I should imagine t h e r e must be some f iner medium betweent h e m , by which these operations were performed."

F r a n k l i n d i s c o v e r e d a t a very e a r l y date the p o w e r p o s s e s s e dby a L e y d e n jar d i s c h a r g e of i m p a r t i n g p e r m a n e n t m a g n e t i s mt o a s t e e l n e e d l e , as well as t o i t s p o w e r of r e v e r s i n g the p o l a r -i t y of the m a g n e t i c n e e d l e . It was k n o w n long b e f o r e F r a n k -l i n ' s t ime that l i g h t n i n g s t r o k e s , s t r i k i n g a s h i p , f r e q u e n t l y re-s u l t e d in a c h a n g e in the polar i ty of the m a g n e t .

F r a n k l i n t h u s r e f e r s t o this p h e n o m e n o n in a l e t t e r t o Col-l i n s o n d a t e d J u l y 27, 1 7 5 o :

"His compasses lost the vir tue of the load-stone, o r the poles werereversed; the N o r t h p o i n t tu rn ing to the South.--By electricity we have(here at Philadelphia) frequently given polarity to needles, and reversed itat pleasure. Mr. Wilson, at Lo~rdon, t r i ed it o n too large masses and withtoo small force.

"A shock from four large jars, sent through a fine sewing needle, givesit l~olari~y, and it will traverse when laid on water . - - I f the needle whenst ruck lies East and West the end e n t e r e d by the electric blast points North.- - I f it lies N o r t h and South the end that lay toward the N o r t h will con-tinue to p o i n t N o r t h when placed o n water , whether the fire e n t e r e d atthat end, o r at the contrary end.

"The Polarity given is s t rongest when the needle is s t ruck ly ing N o r t hand South, weakest when ly ing East and W e s t ; perhaps if the force wasstill g rea te r , the South end, enter'd by the fire, (when the needle lies N o r t hand South) migh t become the N o r t h , otherwise it puzzles us t o account forthe inverting of compasses by l ightning; since the i r needles must alwaysbe found in that situation, and by our little Experiments, whether the blaste n t e r e d the N o r t h and went out at the South end of the needle, o r the~ o n t r a r y , still the end that lay to the N o r t h should cont inue to point..North.

" I n these experiments the ends of the needles are sometimes finelyblued like a watch-spring by the electric flame.--This colour given by theflash from two jars only, will wipe off, but four jars fix it and frequentlymelt the needles. I send you some that have had the i r heads and pointsme l t ed off by our mimic l ightning; and a pin that had its point melted off,:and some part of its head and neck run. Sometimes the surface of thebody of the needle is also run, and appears blister'd when examined by a:magnifying glass: the jars I made use of hold 7 o r 8 gallons, and are,coated and lined with tin foil; each of them takes a thousand t u r n s of ag l o b e nine inches diameter to charge it."

It is p l e a s i n g t o r e c o r d that F r a n k l i n did n o t p e r m i t his en-

May, I9O6.] Franklin as aMan of Scienec and an Inventor. 37 I

thusiasm for the g r e a t science of electricity t o lead him t oa d o p t all k i n d s of foolish t h e o r i e s c o n c e r n i n g i ts therapeuticand c u r a t i v e powers . T h e r e are so m a n y apparently mysteri-ous properties possesed by electricity, that one not possessinga philosophic m i n d m i g h t r e a d i l y be led t o b e l i e v e a l m o s t anys t a t e m e n t m a d e c o n c e r n i n g the p o w e r s of this s t r a n g e force.It is for this r e a s o n t h a t electricity h a s a lways been a favoriter e m e d y wi th q u a c k s and charlatans, possibly in the h o p e s tha t ,s i n c e so little is r e a l l y k n o w n c o n c e r n i n g this force, they c o u l dthe m o r e safely draw on t h e i r i m a g i n a t i o n as r e g a r d s i ts c u r a -tive powers .

I t is true that at the e a r n e s t r e q u e s t of many p e o p l e suffer-ing from paralysis , F r a n k l i n c o n s e n t e d t o t r e a t them by thed i s c h a r g e of the L e y d e n jar; bu t , as he afterwards acknowl-e d g e d , this t r e a t m e n t did n o t a p p e a r t o p r o d u c e any p e r m a n e n tbenefits. H e thus r e f e r s t o the m a t t e r in a l e t t e r wri t ten t oj o h n P r i n g l e , d a t e d D e c e m b e r 2I, I 7 5 7 :

"In compliance with your request, I send you the following accountof what I can at present recollect relating to the effects of electricity inparalytic cases, which have fallen under my observation.

"Some years since, when the newspapers made mention of greatcures performed in Italy and Germany, by means of electricity, a numbero.¢ paralytics were brought to me from different parts of Pennsylvania, andthe neighbouring provinces, to be electrised, which I did for them at theirrequest. My method was, to place the patient first in a chair, on an elec-tric stool, and draw a number of large, strong sparks from all parts of theaffected limb or side. Then I fully charged two six-gallon glass jars, eachof which had about three square feet of surface coated; and I sent theunited shock of these through the affected limb or limbs, repeating thestroke commonly three times each day. The first thing observed was animmediate greater sensible warmth in the lame limbs that had receivedthe stroke, than in the others; and the next morning the patients usuallyrelated, that they had in the night felt a pricking sensation in the flesh ofthe paralytic limbs; and would sometimes shew a number of small red spotswhich they supposed were occasioned by those prickings. The limbs, too,were found more capable of voluntary motion, and seemed to receivestrength. A man, for instance, who could not the first day lift the lamehand from off his knee, would the next day raise it four or five inches, thethird day higher, and the fifth day was able, but with a feeble, languid mo-tion, take off his hat. These appearances gave great spirit to the patients,and made them hope a perfect cure; but I do not remember that I eversaw an amendment after the fifth day; which the patients perceiving, andfinding the shocks pretty severe, they became discouraged, went home, andin a short time relapsed; so that I never knew any advantage from elec-

3 7 2 Houston: [J. F. I.,

tricity in palsies that was permanent. And how far the apparent tempo-rary advantage migh t arise from the exercise in the patients journey, andcoming daily to my house, or from the spirits given by the hope of success,enabling them to exer t more s t r eng th in m o v i n g the i r limbs, I will notpretend to say.

"Perhaps some permanent advantage migh t have been obtained, if theelectric shocks had been accompanied with p r o p e r medicine and regimen,under the direction of a skillful physician. I t may be, too, that a few greatstrokes as given in m y method, may not be so p r o p e r as many small ones ;since, by the account from Scotland, of a case, in which two hundred shocksfrom a phial were given daily, it seems, that a per fec t cure has been made.As to any uncommon strength supposed to be in the machine used in thatcase, I imagine it could have no share in the effect produced; since thestrength of the shock from the charged glass, is in proportion to the quan-tity of the glass coated; so that my shocks from those large jars, musthave been much grea ter than any t h a t could be received from a phia l heldih the hand ."

As to the probability of so-called electrical medication; i. e.,of causing electrified drugs, placed inside of glass vessels, to bepassed through the walls of the vessel into bodies of patients inthe shape of medicated effluvia, Franklin expresses himself verydecidedly as follows:

"Hence we see the impossibility of success in the experiments pro-posed, to draw out the effluvial vi r tues of a non-electric, as cinnamon, forinstance, and mix ing them witk the electric fluid, to convey them with t h a tinto the body, by including it in the globe, and then applying friction, &c.For though the effluvia of cinnamon and the electric fluid should mix withinthe globe, they would neve r come out toge the r through the pores of theglass, and so go to the pr ime conductor; for the electric fluid itself cannotcome th rough ; and the pr ime conductor is always supply'd from the cush-ion, and that from the floor. And besides, when the globe is filled withcinnamon, o r o t h e r non-electric, n o electric fluid can be obta ined from itsou te r surface, for the reason before-mentioned. L have t r i ed another way,which I though t more likely to obtain a mix ture of the electric and o t h e reffluvia together, if such a mix ture had been possible. I placed a glassplate under my cushion, to cut off the communication between the cushionand floor; then brought a small chain from the cushion into a glass of oilof turpentine, and carried a n o t h e r chain from the oil of turpentine to thefloor,taking care that the chain from the cushion to the glass, touch 'd n opar t of the f rame of the machine. A n o t h e r chain was fixed to the pr imeconductor, and held in the hand of a person to be electrised. The ends ofthe two chains in the glass were near an inch distant from each other, theoil of turpentine between. Now the globe being turned, could draw nofire from the floor through the machine, the communication that way be-ing cut off by the t h i c k glass plate under the cushion: it must then drawit through the chains whose ends were dipped in the oil of turpentine. And

May, 19o6.] Franklin as aMan of Science and an Inventor. 373

so the oil of turpentine, being an electric per se, could not conduct, whatcame up from the floor was obliged to jump from the end of one chainto the end of the other, through the substance of that oil, which we couldsee in large sparks, and so it had a fair opportunity of siezing some of thefinest particles of the oil in its passage, and carrying them off with it: ,butno such effect followed, nor could I perceive the least difference in thesmell of the electric effluvia thus collected, from what it has when collectedotherwise, nor does it otherwise affect the body of a person electrised. Ilikewise put into a phial, instead of water, a strong purgative liquid, andthen charged the phial, and took repeated shocks from it, in which caseevery particle of the electric fluid must, before it went through my body,have first gone through the liquid when the phial is charging, and returnedthrough it when discharging, yet no other effect followed than if it had beencharged with water."

Franklin's in teres t in educat ional m a t t e r s was not only evi-ctenced by the valuable papers he w r o t e on such topics, bu t alsoby the practical results which flowed from t h e s e papers , a m o n gwhich are the establishment of the great University of Penn-sylvania, and the American Philosophical Society. I will no tstop to discuss t h e s e foundat ions of Franklin, since I have al-ready described them in a paper prepared for publication in thefournal of the Franklin Insti tute. It is interest ing, however,to note, in this connection, tha t t h e r e is another character ofwork for which Franklin was eminently fi t ted, and in which hem i g h t fairly have claimed a place in the first r a n k ; i. e., as ateacher o f natural science.

Franklin not only possessed the rare ability of being able tothoroughly unders tand the causes of natural phenomena, bu the also possessed the still r a r e r ability of being able to i m p a r this ideas concerning such phenomena to others . This , I think,was the natural result of the logical methods employed byFranklin in his scientific investigations. The successive stepstaken by him in his experimental researches were never madein a haphazard manner, bu t invariably followed one another instrict logical sequence, and when he endeavored to i m p a r tt h e s e principles to others , he always so presented them that thesuccessive s t eps of his explanation followed the same strictlogical order of sequence.

To a certain extent, all of Franklin's letters and papers areproperly to be regarded as a species of scientific instruction tothe public. The many quota t ions I have given from some ofthe more important of t h e s e papers will enable one readily to

374 Houston: [J. F. I.,

form an idea as t o the c l e a r m a n n e r in w h i c h they were writ ten.The style of t h e s e p a p e r s m a y still be r e g a r d e d as an a d m i r a b l ee x a m p l e of scientific t e a c h i n g .

In this connection, w e s h o u l d not lose s i g h t of the i m p o r t a n trole w h i c h the J u n t o , the s e l e c t scientific d e b a t i n g and l i t e r a r ysociety f o r m e d by a few of F r a n k l i n ' s i m m e d i a t e friends, p l a y e din the d e v e l o p m e n t of this side of F r a n k l i n ' s character. Thenecessity i m p o s e d on each of the m e m b e r s of this S o c i e t y t op r e p a r e papers on v a r i o u s t o p i c s at more ov less r e g u l a r i n t e r -v a l s ; t o read such p a p e r s b e f o r e the Society; and t o take part inthe discussion of s i m i l a r p a p e r s p r e p a r e d by o t h e r m e m b e r s ,c o u l d not have failed t o d e v e l o p any l a t e n t pc~wers of t e a c h i n gthat m a y have been possessed by the different individual m e m -b e r s . I t h i n k t h e r e can be n o d o u b t but that this p h a s e of theJ u n t o g r e a t l y i m p r o v e d F r a n k l i n ' s p o w e r s in this respect .

An a d m i r a b l e e x a m p l e of F r a n k l i n ' s rare abili ty a s a t e a c h e ris t o be had in a s e r i e s of letters on scientific subjects w r i t t e nt o a little g i r l , a Miss S - - n , at W a n s t e a d . I will give only ab r i e f q u o t a t i o n from one of t h e s e letters, d a t e d May 17, I 7 6 o :

"I send my dear, good girl the books I mentioned to her last night.I beg her to accept them as a small mark of my esteem and friendship.They are written in the familiar, easy manner for which the French areso remarkable, and afford a great deal of philosophic and practical know-ledge, unembarres'd with the dry mathematics used by more exact reason-ers, but which is apt to discourage young beginners.--I would advise youto read with a pen in your hand, and enter in a little book short hints ofwhat you find there that is curious, or that may be useful; for this will bethe best method of imprinting such particulars in your memory, where theywill be ready, either for practice on some future occasion, if they are mat-ters of utility; or at least to adorn and improve your conversation, if theyare rather points of curio.sity.--And, as many of the terms of science aresuch as you cannot have met with in your common reading, and may, there-fore be unacquainted with, I think it would be well for you to have a gooddictionary at hand, to consult immediately when you meet with a w,rdyou do not comprehend the precise meaning of. This may a t first see,ntroublesome and interrug.ting; but 'tis a trouble that will daily diminish,as you will daily find less and less occasion for your Dictionary as you be-come more acquainted with the terms; and in the meantime you will readwith more satisfaction because with more understanding.--When any p,.intoccurs in which you would be glad to have farther information than yourbook affords you, I beg you would not in the least apprehend that I .~houldthink it a trouble to receive and answer your questions. It wil! be apleasure, and no trouble. For though I may not he able, out of my own

~Iay, x9o6.] Franklin as aMa~ of Science and a~t Inventor. 375

little stock of knowledge to afford you what you require, I can easily di-rect you to the books where it may most readily be found."

In this s e r i e s of l e t e t r s will be f o u n d some c h a r m i n g t e a c h -ing c o n c e r n i n g a v a r i e t y of scientific m a t t e r s , t o w h i c h it will b eimpossible here t o do more than briefly r e f e r ; for e x a m p l e , whybarometers, a l t h o u g h p l a c e d in r o o m s wi th the windows andd o o r s shu t , can give the p r e s s u r e of the o u t e r air; or, even ifthe windows and d o o r s be o p e n , how can the pressure of theair act on the m e r c u r y in an apparently t i g h t l y c l o s e d vessel;b e s i d e s o t h e r interesting m a t t e r w h i c h will a m p l y r e p a y a c l o s eperusal, on a c c o u n t of the e x c e l l e n t m e t h o d e m p l o y g d in im-p a r t i n g the information. In one of t h o s e letters, F r a n k l i n g i v e shis e x p l a n a t i o n as t o the r e a s o n of a well-known fact ; viz. , thatit is possible t o uti l ize the p o w e r possesed by the skin of ab-s t r a c t i n g f r e s h w a t e r from the very salt w a t e r of the o c e a n .l i e c a l l s a t t e n t i o n t o this m a t t e r as follows: . , .... ,

"I have a singular opinion on this subject, which I will venture to com-municate to you, though I doubt you will rank it among my whims.--Itis certain that the skin has imbibing as well as discharging pores; witness theeffects of a blistering plaister, &¢.. I have read that a man hired by aphysician to stand by way of experiment in the open air naked during amoist night weighed near three pounds heavier in the morning. I haveoften observed myself that however thirsty I may have been before goinginto the water to swim, I am never long so in the water. These imbibingpores, however, are very fine, perhaps fine enough in filtering to separatesalt from water; for though I have soaked by swimming, when aboy, several hours a day for several days successively in salt-water,I never found 'my blood and juices salted by that means, so as to makeme thirsty or feet a salt taste in my mouth: And it is remarkable that theflesh of sea fish, though bred in salt water is not salt.--Hence I imagine,that if people at sea, 'distressed by thirst when their fresh water is unfor-tunately spent, would make bathing tubs of their empty water cssks, andfilling them with sea water sit in them an hour or two each day, they mightbe greatly relieved. Perhaps keeping their cloaths constantly wet mighthave an almost equal effect, and this without danger of catching cold. Mendo not catch cold by wet cloaths at se~. Damp but not wet linen may pos-sibly give colds; but no one catches cold by bathing, and no cloaths canbe wetter than water itself. Why damp cloaths should then occasion colds,is a curious question, the discussion of which I reserve for a future letter,or some future conversation."

In his autobiography, F r a n k l i n speaks of his fondness fors w i m m i n g , as well a s the fact tha t , when a b o u t twen ty y e a r s

376 Houston: [J. F. I.,

of age, while at W a t t ' s Printing House, he taught an acquaint-ance the art of swimming in two lessons. He thus refers tothis fact in his autobiography as follows:

"At W a t t ' s printing-house I entracted an acquaintance with an in-genious young man, one Wyga te , who, havinff weal thy relations, had beenbe t t e r educated than most printers; was a tolerable Latinist, spoke Frenchand loved reading. I t aught him and a friend of his to swim, at twice go-ing into the river, and they soon became good swimmers. They intro-duced me to some gent lemen from the country, who went to Chelsea bywater, to see the College and Don Saltero 's curiosities. I n our re tu rn , atthe request of the company, whose curiosity W y g a t e had excited, I strippedand leaped into the water and swam from near Chelsea to Blackfriars; per-forming in the way many feats of activity, both upon and under the water ,that surprised and pleased those t o whom they were novelties.

" I had from a child been del ighted with this exercise, had studied andpractised Thevenot's motions and positions, and added some of my own,a iming at the graceful and easy, as well as the useful. All these I tookthis occasion of exhibiting to the company, and was much flattered by the i radmiration; and Wyga te , who was desirous of becoming a mas te r , grewmore and more attached to me on t h a t account, as well as from the simi-larity of our studies. He at leng th p roposed to me travelling all overEurope together, supporting ourselves everywhere by working at our busi-ness. I was once inclined to it, ~)ut mentioning it to my good friend Mr.Denham, with whom I often spen t an hour when I had leisure, he dis-suaded me from it; advis ing me to'think only of returning to Pennsylvania,which he was now about t o do."

At a later date, F r a n k l i n w r i t e s th~ following as regards thebest manner for a person to acquire this art without a teacher :

" I cannot be of opinion with you that 'tis too late in life for you t olearn to swim. The r iver near the b o t t o m of your garden affords a mostconvenient place for the purpose. And as your new employment requiresyour often being on the water , of which you have such a dread, I t h i n kyou would do well t o make the t r ia l ; nothing being so likely to removethose apprehensions as the Consciousness of an ability to swim to the shore ,iu case of an accident, or of supporting yourself in the water till a boatcould come to take you up.

" I do not know how far corks and bladders may be useful in lea rn ingt o swim, having neve r seen much t r ia l of them. Possibly they may be ofservice in supporting the body while you are lea rn ing what is called thestroke, o r t h a t manne r of drawing in and striking out the hands and feetthat is necessary to produce progress ive motion. But you will be no swim-mer unt i l you can place some confidence in the power of the water to sup-por t you; I would therefore advise the acquir ing of t h a t confidence in thefirs t place; especially as I have known several who by a little of the prac -

May, 19o6.] Franklin as aMan of Science "and an [~zventor. 377

rice necessary for that purpose, have insensibly acquired the stroke, taughtas it were by nature.

"The practice I mean is this. Chusing a place where the water deepensgradually, walk cooly in until it is up to your breast, then turn round, yourface to the shore, and throw an egg into the water between you and theshore. It will sink to the bottom, and be easily seen there, as your wateris clear. It must lie in water so deep that you cannot reach it to takeit up but by diving for it. To encourage yourself in undertaking to dothis, reflect that your progress wiII be from deeper to shallower water, andthat at any time you may, by bringing your legs under you and standing onthe bottom, raise your nead far above the water. Then plunge under itwith your eyes open, throwing yourself towards the egg, and endeavour-ing by the action of your hands and feet against the water to get forwardtill within reach of it. In this attempt you will find, that the water buoysyou up against you'r inclination; that it is not so easy a thing to sink asyou imagined; that you cannot, by your active force, get down to the egg.Thus you feel the power of the water to support you, and learn to confidein that power; while your endeavours to overcome it and reach the egg,teach you the manner of acting on the water with your feet and hands,which action is afterwards used in swimming to support your head higherabove water, or to go forward through it."

I n the p r e c e d i n g p a g e s , I have e n d e a v o r e d briefly t o give a na c c o u n t of the m a n y d e p a r t m e n t s of physical science that havebeen c o v e r e d by the g r e a t e x p e r i m e n t a l philosopher w h o s ework I have e n d e a v o r e d t o t r a c e . I t is a m a t t e r of no littler e g r e t t o m e that the many c a l l s of a busy professional life havenecessitated m y d o i n g this work in so incomplete a n d h u r r i e d am a n n e r . The c h a r a c t e r of the work that is u n d e r r e v i e w is ofsuch a t y p e that i ts discussion d e s e r v e s a m u c h more c a r e f u lt r e a t m e n t than I have been able t o g i v e it. If, however, thisw o r k h a s the e f f e c t of a t t r a c t i n g a m o r e careful a t t e n t i o n t o thescientific work of F r a n k l i n , I s h a l l feel m o r e than c o m p e n s a t e dfor the l a b o r w h i c h even t h e s e h u r r i e d p a g e s have necessitated.B u t h o w e v e r i m p e r f e c t the c h a r a c t e r of m y w o r k , I feel con-v i n c e d that a c a r e f u l p e r u s a l c a n n o t fail t o i m p r e s s t h o s e whoa r e c a p a b l e of j u d g i n g w o r k of this c h a r a c t e r that B e n j a m i nF r a n k l i n m a y b e p r o p e r l y r e g a r d e d , m

(i) As the first g r e a t A m e r i c a n electrician.(2) As a n a t u r a l philosopher of the h i g h e s t t ype , bo th in

l h e d o m a i n s of g e o g r a p h i c a l physics and applied physics .(3) As an i n v e n t o r of the h i g h e s t t ype .F r a n k l i n d e m o n s t r a t e d his r i g h t t o the tit le of the first g r e a t

A m e r i c a n electrician, n o t only by his f a m o u s e x p e r i m e n t wi th

378 Houstou: [J. F. I.,

the kite , but also by o t h e r electrical w o r k , such as, for e x a m p l e ,his single-fluid electrical h y p o t h e s i s , his m a s t e r f u l a n a l y s i s o fthe m a n n e r in w h i c h the L e y d e n jar r e c e i v e s and p a r t s with i t sc h a r g e , as well as by the n u m e r o u s p a p e r s on a g r e a t v a r i e t y ofelectrical s u b j e c t s t o w h i c h a t t e n t i o n has b e e n briefly c a l l e d inthe p r e c e d i nK p a g e s .

H e d e m o n s t r a t e d his r i g h t t o the t i t l e of a g r e a t n a t u r a l phi-l o s o p h e r by the w o n d e r f u l skill m a n i f e s t e d in investigations on.a g r e a t var ie ty of physical s u b j e c t s , t o w h i c h also a t t e n t i o n h a sbeen c a l l e d . The mind of the g r e a t m a s t e r is. c l e a r l y e x h i b i t e d 'in t h e s e investigations, not only by the g r e a t r e s u l t s achieved,.but especially by the l o g i c a l m a n n e r in w h i c h the d e t a i l e d facts.w e r e c o n c e i v e d and c a r r i e d out .

It is especially i n t e r e s t i n g , in this connection, t o bear in.mind the g r e a t var ie ty of such investigations that w e r e em-b r a c e d in the field of g e o g r a p h i c a l p h y s i c s a l o n e , e m b r a c i n gas they did, the c a u s e s and p h e n o m e n a of the a u r o r a borealis,.t h u n d e r - g u s t s , w a t e r s p o u t s , w h i r l w i n d s , the g r e a t n o r t h e a s ts t o r m s of the U n i t e d S t a t e s , the Gul f S t r e a m , the electrificatiortof c l o u d s , &c.

F r a n k l i n ' s r i g h t t o the t i t l e of one of the g r e a t e s t of the e a r l yA m e r i c a n inventors is b a s e d on a v a r i e t y of i m p o r t a n t w o r k ,s u c h , for e x a m p l e , as the i n v e n t i o n of the l i g h t n i n g rod, of t h ePennsylvania fire-place, of the s t o v e with the i n v e r t e d d r a u g h t , .of the p r o p e r c o n s t r u c t i o n of chimrmys," the venti lat ion ofb u i l d i n g s and m i n e s , the b i f o c a l spectacles, etc .

I have received t h r o u g h the k i n d n e s s of Mr. A u g u s t i n e B i e s e l o fthe A m e r i c a n E m b a s s y in P a r i s , t h r o u g h the h a n d s of Mr.J o s e p h G. R o s e n g a r t e n , of Philadelphia, a p h o t o g r a p h of theG r e u z e p o r t r a i t of F r a n k l i n , from w h i c h the a c c o m p a n y i n gp l a t e was m a d e .

B e f o r e c o n c l u d i n g this p a p e r on F r a n k l i n , I t h i n k it well t ogive w i t h o u t f u r t h e r c o m m e n t , the full text of a p a p e r , p r e p a r e din P a r i s , by s p e c i a l r e q u e s t , c o n c e r n i n g his g r e a t i n v e n t i o n ofl i g h t n i n g r o d s . A s the i n v e n t o r of l i g h t n i n g r o d s , F r a n k -lin n a t u r a l l y had his a t t e n t i o n r e p e a t e d l y c a l l e d t o w e l t m a r k e dl i g h t n i n g s t r o k e s in different p a r t s of the w o r l d , so that he h a dan oppor tuni ty of a s c e r t a i n i n g in w h a t r e s p e c t s r o d s e r e c t e d ina c c o r d a n c e with his d i r e c t i o n s failed in t h e i r abili ty t o p r o t e c tthe b u i l d i n g s on w h i c h they w e r e p l a c e d . W e woutdl, c o n s e -

~'iay, 19o6.] Franklin as aMan of Science a~,d an Inventor. 379

q u e n t l y e x p e c t t o f ind i n th i s p a p e r a m u c h m o r e c o m p l e t e ac-c o u n t o f F r a n k l i n ' s v i e w s o n t h e s u b j e c t t h a n w o u l d be f o u n din his o t h e r p a p e r s :

"Of Ligh tn ing and the M e t h o d (now used in America) of securingBuildings and P e r s o n s from its mischievous Effects.

"Experiments made in electricity firs t gave philosophers a suspicionthat the matter of lightning was the same with electric matter. Experi-ments afterwards made on lightning obtained from the clouds by pointedrods, received in bottles, and subjected t o every trial, have since provedthis suspicion t o be perfectly well founded; and that whatever propertieswe find in electricity, a re also the properties of lightning.

"This matter of lightning, o r electricity, is an extream subtle fluid,penetrating o t h e r bodies, and subsist ing in t h e m , equally diffused,

" W h e n by any operation of ar t o r na ture , t h e r e happens to be a grea terproportion of this fluid in one body than in another, the body which hasmost, will communicate to that which has least, till the proportion becomesequal; provided the distance between them be not too grea t ; or, if it istoo great, till t h e r e be p r o p e r conductors to convey it from one to theother.

"If the communication be through .the air without any conductor, abr ight l ight is seen between the bodies, and a sound is heard. I n oursmall experiments we call this l ight and sound the electric spark and snap;but in the grea te r operations of nature, the l ight is what we call lightning,and the sound (produced at the same time, tho' generally arriving la te rat our ears than the l ight does to our eyes) is, with its echoes, calledthunder.

"If the communication of this fluid is by a conductor, it may be withouteither l ight o r sound, the subtle fluid pass ing in the substance of the con-ductor.

"If the conductor be good and of sufficient bigness, the fluid passesthrough it without hur t ing it. If otherwise, it is damaged o r destroyed.

"All metals , and water , are good conductors.--Other bodies may be-come conductors by having some quantity of water in them, as wood, ando t h e r materials used in building, but not having much water in them, theyare not good conductors, and therefore are often damaged in the opera-tion.

"Glass, wax, silk, wool, feathers, and even wood, perfectly dry are non-conductors: that is, they resist instead of facilitating the passage of thissubtle fluid,

" W h e n this fluid has an opportunity of passing through two conductors ,one good, and sufficient, as of metal, the o t h e r not so good, it passes inthe best, and will follow it in any direction.

"The distance at which a body charged with this fluid will dischargeitself suddenly, striking through the air into a n o t h e r body that is notcharged, o r not so highly charg'd, is different according to the quantity ofthe fluid, the dimensions and form of the bodies themselves, and the stateof the air between them.--This distance, whatever it happens to be between

3 8 0 Houston: [J. F. I.,

two 'oodles, is cal led the i r striking distance, as till they come within thatdistance o f each other, no s t roke will be made.

"The clouds have often more of this fluid in proportion than the earth;in which case as soon as they come near enough ( tha t is, within strikingdis tance) o r meet with a conductor, the fluid qui ts them and st r ikes intothe earth. A cloud fully charged with this fluid, if so high as to be beyondthe striking distance from the earth, passes quietly without mak ing noiseo r giving light; unless it meets with other clouds that have less.

"Ta l l t rees , and lofty buildings, as the towers and spires of churches,become sometimes conductors between the clouds and the earth; but notbeing good ones, that is, not conveying the fluid freely, they are oftendamaged.

"Buildings that have the i r roofs covered with lead, o r o t h e r me ta l andspou t s of me ta l continued from the roof into the ground to car ry off thewater , are neve r hurt by lightning, as whenever it falls on such a building,it passes in the meta ls and not in the walls.

" W h e n other q~uildings happen to be within the striking dis tance fromsvch clouds, the fluid passes in the walls whether of wood, brick o r stone,qui t t ing the walls only when it can find be t t e r conductors near them, asmeta l rods, bo l t s and hinges of windows o r doors, gilding on wainscot,or frames of pictures; the silvering on the backs of looking-glasses; thewires for bells; and the bodies of animals, as containing watery fluids.And in pass ing t h r o ' the house it follows the direction of these conduct-ors,taking as many in it's way as can assist it in its passage, whether ina s t ra i t o r crooked line, leaping from one to the other, if not far distantfrom each other, only rending the wall in the spaces where these partialgood conductors are too distant from each other.

"An iron rod being placed on the outside of a building, from the high-est part continued down into the moist earth, in any direction s t ra i t orcrooked, following the form of the roof o r o t h e r parts of the building, willreceive the lightning at its upper end, attracting it so as to prevent itsstriking any o t h e r p a r t ; and, affording it a good conveyance into the earth.will prevent its damaging any par t of the building.

"A small quantity of me ta l is found able to conduct a great quantityof this fluid. A wire no bigger than a goose quill, has been known toconduct (wi th safety to the building as far as the wire was continued) aquantity of lightning that did prodigious damage both above and below it;and probably larger rods are not necessary, tho' it is c o m m o n in America,tc make them of half an inch, some of three-quarters, o r an inch indiameter.

"The rod may ~oe fastened to the wall, chimney, &c., with staples ofiron.--The lightning will not leave the rod (a good conductor) t o pass intothe wall (a bad conductor), through those staples.--It would rather, if anywere in the wall, pass out of it into the rod to get more readily by thatconductor into the earth.

" I f the building be very large and expensive, two o r more rods may beplaced at different par ts , for grea te r security.

May, I 9 o 6 . ] Fra l z k l i n a s a 3 l a l z o f Scic lzce a~*d a~z Inven tor . 3 8 i

"Small , ragged parts of clouds suspended in the air between the greatbody of clouds and the earth (like leaf gold in electrical experiments),often serve as partial conductors for the lightning, which proceeds fromone of them to another, and by the i r help comes within the striking dis-tance to the e a r t h or a building. I t therefore strikes through those con-ductors a building that would otherwise be out of striking distance.

"Long, sharp points, communicating with the earth, and presented tosuch parts of clouds, drawing silently from them the fluid they are chargedwith, they are then attracted to the cloud, and may leave the distance sogreat as to be beyond the reach of striking.

"It is therefore that we elevate the upper end of the rod six o r e ightfeet above the highest par t of the building, tapering it gradually to a fine,sharp point, which ,is gilt, to prevent its rusting.

"Thus the pointed rod either prevents a s t roke from the cloud, or,if a stroke is made, conducts it to the e a r t h with safety to the building.

"The lower end of the r o d should enter the earth so deep as to comeat the moist part, perhaps two or t h r e e feet; and if bent when under t h esurface so as to go in a horizontal line six or e ight feet from the wall,and then ben t again downwards t h r e e o r four feet, i t will prevent damageto any of the stones of the foundation.

"A person apprehensive of danger from lightning, happening in t h etime of thunder to be in a house not so secured, will do well to avoidsitting near the chimney, near a looking-glass o r any gilt pictures o rwainscot; the safest p lace is in the middle of the r o o m , (so it be not undera metal lustre suspended by a chain) sitting in one chai r and laying t h efeet up in another. I t is still safer to br ing two o r t h r e e mattrasses orbeds into the middle of the room, and folding them up double, p lace thechair upon t h e m ; for they not being so good conductors as the walls, thelightning will not chuse an interrupted course through the air of the r o o mand the q)edding, when it can go t h r o ' a be t t e r continued conductor, thewall. But where it can be had, a hammock or swinging bed, suspended bysilk cords equally d is tan t from the walls on every side, and from the ceilingand floor above and below, affords the safest situation a person can havein any room whatever; and what indeed may be deemed qui te free fromdanger by any s t roke by lightning."

F r a n k l i n died o n t h e I 7 t h o f A p r i l , i 7 9 o . T h e C o n g r e s s o ft h e U n i t e d S t a t e s , w h i c h w a s in s e s s i o n a t t h e t ime o f his d e a t h ,p a s s e d t h e f o l l o w i n g r e s o l u t i o n o n t h e r e c e i p t o f t h e sad n e w s :

"The House, being informed of the decease of Benjamin Franklin, acitizen whose native genius was not more an ornament t o human na turethan his various exertions of it have been precious to science, to freedom,and to his country, do resolve, as a mark of the veneration due to hism e m o r y that the members wear the customary b a d g e of mourn ing for onemonth."

A h i g h e r h o n o r w a s p a i d t o his m e m o r y b y t h e N a t i o n a l A s -

382 Houston: [J. F. I.,

s e m b l y of F r a n c e on the m o r n i n g a f t e r the intel!igence reacheclP a r i s , on June II. The a s s e m b l y was c o n v e n e d , when Mira-beau s p o k e a s follows:

"Franklin is dead! The genius, that freed America and poured a floodof light over Europe, has returned to the bosom of the Divinity.

"The sage whom two worlds claim as their own, the man for whom thehistory of science and the history of empires contend with each other, held,without doubt, a high rank in the human race."

"Too long have political cabinets taken formal note of the death ofthose who were great only in their funeral panegyrics. Too long has theetiquette of courts prescribed hypocritical mourning. Nations should wearmourning only for their benefactors. The representatives of nations shouldrecommend to their homage none but the heroes of humanity.

"The Congress has ordained, throughout the United States, a mourn-ing of one month for the death of Franklin; and, at this moment, Americais paying this tribute of veneration and gratitude to one of the fathers ofher Constitution.

"Would it not become us, Gentlemen, to join in this religious act, tobear a part in this homage, rendered, in the face of the world, both to therights of the man, and to the philosopher who has most contributed toextend their sway over the whole earth? Antiquity would have raised altarsto this mighty genius, who, to the advantage of mankind, compassing inhis mind the heavens and the earth, was able to restrain alike thunderboltsand tyrants. Europe, enlightened and free, owes at least a token of remem-brance and regret to one of the greatest men who have ever been engagedin the service of philosophy and of liberty.

"I propose that it be decreed, that the National Assembly, during threedays, shall wear mourning for Benjamin Franklin."

On the a d o p t i o n of this m o t i o n by acclamation, the As-s e m b l y d e c r e e d that on the I4 th day of J u n e , they w o u l d goin to m o u r n i n g for t h r e e days, and d i r e c t e d the P r e s i d e n t of theA s s e m b l y t o w r i t e a l e t t e r of c o n d o l e n c e t o the C o n g r e s s ofthe U n i t e d States.

It h a s been falsely a l l e g e d that F r a n k l i n was a n irreligiousm a n . A n assertion of this kind s u r e l y c o u l d n o t have beenmade by a n y o n e c o n v e r s a n t wi th F r a n k l i n ' s writings. I willm e r e l y q u o t e a l e t t e r w r i t t e n by F r a n k l i n , on M a r c h 9, I 7 9 ° ,:shortly b e f o r e his d e a t h , in w h i c h he says :

"You desire to know something of my religion. It is the first timeI have been questioned upon it. But I cannot take your curiosity amiss,:and shall endeavour in a few words to "gratify it. Here is my creed: Ibelieve in one God, the creator of the universe. That he governs it by-his Providence. That he ought to be worshipped. That the most accept-

~ a y , I9o6.] Franklin as aMan of Science and an Inventor. 3 8 3

a b l e service we r e n d e r t o h i m is d o i n g g o o d t o h i s o t h e r c h i l d r e n . . T h a tthe s o u l of m a n is immortal, and will ~be treated w i t h jus t i ce i n a n o t h e r liferespec t ing i t s c o n d u c t i n t h i s . T h e s e I take t o be the f u n d a m e n t a l p o i n t si n all s o u n d re l i g ion , and I r e g a r d them as y o u d o i n w h a t e v e r sect I m e e tw i t h t h e m . "

I f , h o w e v e r , t h i s t e s t i m o n y h a d b e e n w a n t i n g , o r i f a n y o n es h o u l d a l l e g e t h a t t h i s w a s m e r e l y t h e o p i n i o n o f a m a n w h oh a d n e a r l y r e a c h e d t h e e n d o f h i s l i f e , t h e f o l l o w i n g e p i t a p h p r e -p a r e d b y F r a n k l i n , w h e n a t t h e a g e o [ b u t t w e n t y - t h r e e y e a r s ,~ v o u l d p r o v e t h e i n c o r r e c t n e s s o f t h e c o n c l u s i o n :

" T h e BodyOf

B e n j a m i n Frank l in .Pr in te r ,

( L i k e the c o v e r of an o l d b o o k ,I t s con ten t s to rn o u t ,

And s t r i p t of i t s l e t t e r ing and g i ld ing , )Lie~ h e r e , food for w o r m s .

But the w o r k s h a l l n o t be l o s t ,F o r i t will, as he be l i eved , a p p e a r once m o r e ,

I n a new and m o r e elegant e d i t i o n ,Revised and corrected

B yT h e Author . "

T H E A L U M I N U M I N D U S T R Y A N D T H E H A L L P A T E N T .

Of n o l i t t l e s ignif icance t o the aluminum indus t ry i n the U n i t e d S t a t e smas the expira t ion o n Apr i l 2, I9o6, of the p a t e n t of C h a r l e s M. H a l l ,g r a n t e d o n A15ril 2, I 8 8 9 , and u n d e r w h i c h i t has been p o s s i b l e for the P i t t s -b u r g h Reduct ion C o m p a n y t o m a i n t a i n a l m o s t a m o n o p o l y of p roduc t ion i nthe U n i t e d Sta tes . Recent ly the d e m a n d has been s o h e a v y that t h i s c o m -pany has n o t been a b l e t o keep u p w i t h i t and domest ic c o n s u m e r s havet u r n e d t o E u r o p e , b u t even at the h i g h p r i c e s pa id a b r o a d i t has n o t beenp o s s i b l e t o ob ta in any cons ide rab le q u a n t i t i e s . T h e l a r g e requirements ofthe au tomobi le indus t ry are r e s p o n s i b l e chiefly for the expansion i n thed e m a n d i n r e c e n t years . R e f e r r i n g t o the expira t ion of the Hal l pa ten tand i t s e f f e c t o n a l u m i n u m m a n u f a c t u r e the Metal Industry m a k e s the ~ol-l o w i n g in te res t ing statement:

I t will be r e m e m b e r e d that t h i s pa t en t , w h i c h b e c a m e of f u n d a m e n t a li m p o r t a n c e for the c o m m e r c i a l p roduc t ion of a l u m i n u m , protec ted the u s eof an e lec t ro ly te c o m p o s e d of c r y o l i t e as a so lven t for bauxite, and t h i se l ec t ro ly te had the most i m p o r t a n t p r o p e r t y of b e i n g eas i ly fusible . T h e