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ASOeeilSSFllt fOM OflNBtieimN BALANCE . #». f llEsmSLESS PifiB^ m imLLKJ MASSES (A jHipor !^^ befoj* til* ABaericwt Apwciatloti for tJie MT»i»<»<»ine«t M ,, /8ii«>iiob, at toe Mtopj^al .meetliJif, Afls^t, ifB8^) v, •- r'.'- if .; ■( I- r ■•;' WI-FH ;Al^, A^PPE S0R nO^tiLlIIB 'clBoteA^ ^9SS SiJ- asi 1 « iMS2 -' ^^^M&fiMMMMMawfiM Sis 4 •V- '.? ■• ':■..•* fW, < ^ - 1* / '■ ■■' A , X-':'B:^" .'"^^ ;i;t''''V' . u- ■ '^''. ^ I \- if 'A' '• .1 - ' . :ii. ..{4\ . UPON THK ELKCTKICAL EXPKHIMKiNTS TO DETEKMINK THE LO(!ATION OF THE BULLET IN THE BODY OF THE LATE PKEalDENT GAHFIELl); AND UPON * A SUCCESSFUL FORM OF INDUCTION BALANCE FOR THE PAINLESS DETECTION OF METALLIC MASSES IN THE HUMAN BODY.' By Alex AN DEK Graham Bkll. (A paper reiul iHifore the Ainericnu AHMotriiitioti for the Advaicement of Soieuce, Ht the Montreal meeting, AvigUHt, 1882.) , 4#-S':' Thk Hiiujcci of my preHetit paper rei-alli* a time of intense excitement and painful 8Usponse. The long, weary struggle with the untimely death-wound — the prolonged suffering borne BO bravely and well by the lamented President Garfield — nuist still be fresh in every rec-oUjction. The wln)le world watched by his bedside, and hopes and fears tilled every pass- ing hour. No one could venture to predict the end so long as the position of the bullet remained unknown. The bullet might become safely encysted, but, on the other hand, recovery might depend upon its extraction. The search with knife and probe among vital and sensitive tissues could rut be otherwise than painful and dangerous ; and the thought naturally arose that science should be able to discover some less barbarous method of exploration. Among other ideas'* the thonglit occurred that the bullet might produce some sensible effect in modifying the Held of ' A prelimiuiiry uotic*! relating to this paper was publiHhed in the Cmnpte* Bendwi of the French Academy of Sciences, Oct. 24th, 1881. ^ Hee Appendix, note 1. mmmmmmmiamititttliMKatL M mml iiiiliictioii III' II coil Itroii^lit iiimr tlif> ImmIj of tlm I'l'eHult^nt, ami tliiit tilt) Inciilily of t'iKt liiillet iiii<;lit tliUH In; (lotfriniiUMl with- out fliiiiffcr to tlif |iHticiif hikI svitlioiit puiii ; for it ii* well known tliiit iiidiu-tioii Clin Ix' powcri'iillv cxiu'tcii tlirongli the linniHii l»oiHation wliatuvur. f'/inii fill' liiililiirinif of /inliii't'ioit, Tlic infiniMic«! tlmt is cxcrcincd ii|)on induction l>y nu-tallio. niassi's lias fornuKJ tiic snl»juc,t of tnnnnrous ox]u'rinicntH l»y dif- ferent invoHtif^atoi'H ; any I'rof. Dove,' al»)ut the year IS41, and a j^ood dest-ription of it in the Kn^lish Ian-- jijuai^e may he foimd in Do la Hive's " Treatise on Electricity," (18r>;i edition, vol. I, pp. 41S-4;?:{)2. Another and superior urranj^ement for the same purjtose is the well-known inilu(i!..n l»alan(re (»f I'rof. 1). E. Ilnghes'. The Stati<' Induction Balance of J. E. II, (iordon* thoufj;h j)rimarily intended for e.\p(M"inu^nts upon spei itic inductive ca- pacity, might also, perhaps, he employed in the same class of investifintioiis. My own atteniion was directed to the Italancang of induction a nmni>er of years ago Ity the disturhing noises produced in the t('lej>lione Ity the opiiration (tf telegraphic instruments upon lines running near the teleplnuie conductor. The ditticulty was remedied hy using two (ronduetors instead of one, and hy so arranging them with referenee to the disturh- ing wires that the currents indiuied in one of the telephone condu(!tors were exactly e«|ual and opposite to those induced in ' P(>KK- Ann. vol. liv, pp. HOr) WXt. ^ A Hiiiiilikr aiipuralviH wiut independently devised in Anierioti li number of yt'iirH ago hy Prof. Rowlund, <»f Jolms Hojikins UniverHity. It it* to he re- gretted thut liiH diBcovery of the fact that he Lad lieen anticipated liy Dove prevente^ to th« Hulijoc^t. In tlio »!onivci of thoso riw<«ar(!liert I niadu frtM|iHMit nsc of tint Hpiralu of iiirtnhitcd wiro, liko tliosc (MnploytMl i>y tiie hkto Prof. Ilonry' in iiis uxpurininntH upon induction. My niotliod waH to paws a rapidly intorrupt(Ml voltaiy nieauK of anotiii^' flat spiral contK^ited with a telephone. The c.urrentH induceil in the latter coil produ(^ed a musical tone from the telephone. At every point in the field of induction it was found that i»y turning the plane of the exploring coil a position of silence couhl lie olitained, and another of maxinnnn sound, the two positions making a right angle with one another. It was also noticed that when a position of silence was estah- lished a piece of metal hrought within the liehl of iiuluctioii eausem a hand ole to rep- telephone, he electro" ken by an ilance was Upon now net ticking tho battery acilities for tir. Oharles fil and "^le- »f his large al iiu;oiive- xperitnents. f apparatus were great rrangeiuent pparatus of a advantage ry form of Hughes' induction balanerder to ad- just the apparatus. These consi'Uirations led me to the eonelii- sion that some moditieation of the Hughes inchietion l)alance was most suitable for my purpose, and I inunediately com- mencied the eonstruction of iiueii an apparatus. Si/(/f/eKfloitN Tested. Just at this time I learned from the newspapers that Prof. Simon Neweond), of Wasliington, had tlie i the ofPer of my assistance in carry- ing on experiments, knowing t!»e comparative ditttculty he woidd experience in having apparatus made in Wasiiington. At Ins suggestion I tested tlie point whether the rotation of a leaden disk and of a leaden huUet underneath a delicately sus- pended magnetic needle would cause a deflection of the needle. The disk ocx^asioned a deflection, but the btdlet produced no sensilde effect. I telegraphed the result to Prof. New(!ond», and at the same time took occasion to inform him of tha hope- ful results I had obtained witii tlie oratory at Washington, where I was accompanied by Mr. Sunnier Tainter, who wis anxious to assist in such a cause. I learned from Prof. Newcomb that Mr. Geo. M. Hopkins, of Brook- lyn, had independently suggested the use of Hughes' induc- tion l)alance, and had may this means. " If larger coils were used the instrument might be operative " at a greater distaiu*, but the area indicated as containing the " ball would be so large that the result would be indefinite and " without value. " Hoping that Prof. Bell will be aide to succeed, I remain, " Yours very truly, "Geo. M. Hopkins." Prof. Hughes of London- England, Prof. Trowbridge of Harvard College, Prof. Rowland of Johns Hopkins University, and other authorities were consulted by telegraph as to the best theoretical form of induction balance for the purpose re([>iiied, while empirical experiments were being carried on under my direction in my laboratory at Washington l»y Mr. Sumner Tainter ; in the electrical work -shop of Davis and Watts, in Baltimore, l»y Mr. J. H. C Watts, and in the estaldishment of Mr. Chas. Williams, Jr., in Boston, by Mr. Thomas A. Gleason. To test the influence of size of coil an instrument was (;on- etr\icted in which the coils were no larger than the bullet for which we sought, (as had been suggested by Prof. New(!omb,)» and experiments were also made with the enormous coils used by the late Prof. Henry in his researches upon induction, which • See Appeudix, note 5. 7J> primary cotla of y'truUtct-itm balance. § were kindly lent to me for the purpose l)y the Sir.ithrtotiiiin Tii- Htih.tioii, l»ut neither the small nor the large coils produced more Hatisfactory resultH than those we had already ol)tained. To test battery power, 20 enormous Bunsen elements, which had formerly been used to light the gas at the (Capitol, were placed at my disposal l»y Mr. Rogers, electrician of the Capitol, but while great elec^tro-motive forc^e was evidently of use we derived no advantage from such a l)attery as this. To test the influence of speed of interruption, Mr. Marean, Supt. of tlie Western Union Telegraph Co. in Washington, kindly lent us an electric motor, by means of which we were able, with the aid of a rotating commutator, to obtain inter- ruptions of the primary circuit of all rates up to 600 interrup- tions per second,! and we . found that the more rapid Ftffo. the rate of interruption the more distinct was the sound in the telephone. The hearing distance, however, was not proportioiuitely increased. The automatic interrupter, (shown in Fig. 5,) yielding about 100 in- terruptions per second, gave as good results as any, and was nuich more conve- nient. This interrupter was therefore afterwards used exclusively in our ex- periments. The theoretical form of coil suggested by Pi'of. John Trow- bridge? was substantially the same as that proposed by Prof. Rowland,'" and is shown in Fig. 6. The arrangement was quite sensitive to metal placied in the • Mr. 8uiuner Tninter has since made nn upparattis operating in a similar manner by means of which he Las obtained as many as 4,000 interruptions of the circuit per second. • '^ See Appendix, note G. ' See Appendix, note 7. 10 interior of the coil, hut the heiiriii^ distiince for a Imllct exter- luil to tlie i!<»il« was no greater than hefore.' Prof. IIuijheH* proposed to have two flat superposed coils wound on a single reel, so that the two coils shonid form a sin- gle one as regards their relative distance ; and Mr. F. T. Bic^k- ford, Washington correspondent of tlie New Voi-k Trihune, suggested winding two wires side l)y side into a single coil, so that the relative distances of the wires from the Itullet should be a'osohitely the same. Mr. Chas. E. Bnell'' and Dr. Chi- chester A. Bell' proposed to determine the depth of the l)ullet beneath the surface by causing a similar bullet to approach the i)alancing coils until silence was restored ; the secondary bullet it was presumed would then l»e at the same distance from the balaiu'ing coils as the embedded bullet from the exploring coils. The results of all the experiments so far nuide were unsatis- factory. I had tried every thing that had been suggested, but 4 (!m. renuiined the extreme limit of audil>ility for a bullet like that whicli IumI struck the President. Even when such a bullet was flatttMied by being flred against a i)oard, and was presented with its flat side towards the coils of the explorer — the most favorable mode of presentation — no better result was obtained. ' The bnlauoo (>1)titine(1 wiw uot ijuito perfect, iind we Imve since discovereil thnt the iuHtiliitiou of the wires of oue of the seeoudury coils wiw defective. ^ Hee A])peudix, iu)te K. ' See Appeudix, note 0. ^ See Appendix, note 10. (52SSi*i»w JVff.r. 11 Oriyhial Kj'jhrriinentK. In the theoretical arrimjijeiMent recomineiided by Profs, Trowhridge and Rowland (Fig. 6) the primary coil A was of finialler diameter tlipti tlie secondary B. This had given lis no better effects than the ordinary form of Hughes' balance, (see Fig. 2,) in whicli the two coils A B were of erjual diameter. We then tried tlie effect of making the primary (^oil A of greater diametei tlian the secondary B, (see Fig. 7,) and in this case we ap- peared to f»btain an in- crease of hearing distance. Five centimetres (2 inch- es) was, iiowever, the ut- most limit reached, wlien, on the 19th of Jul . Mr. J. Stanley Brown and Dr. Woodward visited my laboratory and witnessed some experiments. No difficulty was experieiuied in detecting a l)ullet held in the mouth by passing the exploring c(nl over the<-heek; and the presence of a ffattened bullet hehl in the (denched hand was also readily determined. Dr. Bliss, Dr. Iiey])urn, and Siu-geon-General Barnes visited the laboratory next day and t^xpressed tliemselves as very hopefully impressed by the experiments. These were subsequently repeated in the sui'geon's room at the Executive Mansion for the information of Dr. Frank Hamilton and Dr. Agnew, who also seemed favorai)ly impressed. Such opinions from the surgeons in attendance upon the Presi- dent, and the continued interest shown by Prof. Nawcomb, encourage It was now determined to test the effect of each (involution of the primary coil, so as to arrive smpirically at some idea of ' I desire Hpecially to express my grati ,nde to Dr. Frank Haniiitou for words of eucourageraent spoken at a later date when sympathy and encour- agement were greatly needed. jT^ ■\j «" i M ia iii i w i af'.wu ' .M-ag.!W t j i 18 the bewt shape of c.in the Imri- . zontal rod, was coniuM^ted to another similar coil, (E,) and to a telephone ; and a small brass ring, (C,) which couhl also he moved along the horizontal rod, was used instead of a bullet to disturb the balance. In making an experiment with this apparatus the secondary coil (B) was first placed within the primary ring and in the same plane with it, and the l)alancing coil E was adjusted to produce silence. T'le brass ring C was then moved along the horizontal rod until the balance was sensilily disturbed and the relative distances of the (toils and the brass ring were noted. ('ontiniiing the experiment the coil B was moved a deter- mined distance beytmc'. the plane of A, and the balancing coils again adjusted to silence. The brass ring C was once more caused to disturb the balance, and the new hearing distance was noted. The following are the tabulated results of a series of experiments made on the 19th of July, 1881. The battery employed consisted of six bichromate cells connected in series. .W.- WHM u |i DKTANI H IIHIWIIBN — AB /// m . . EC tit til. AC mm. WW, (» 17 17 5 14 1!) 3U 10 13 23 au » 211 30 7 37 60 50 17 17 n 1» 24 60 10 an 3fl ao 17 37 30 14 44 60 6 55 iil 21 5 23 2H HI 10 23 33 ao IH 3« 30 14 44 60 12 02 22 22 5 25 30 113 10 27 37 20 ! 2(( 4fi 30 2(1 5fi 60 17 «7 If D»TANC> Hktwiibm— AB BC AC mm. mm. mm mm. 27 27 6 20 36 15U 10 18 28 20 l" 37 30 H 44 60 14 M 12 12 5 IH 23 ao6 10 25 36 20 10 3!) 30 22 52 5(1 IH (W 20 20 5 18 23 353 10 1 20 ao 20 I'.l 39 30 . a3 53 60 20 70 Therto figures show that the ilidanee from the primary coil A (Fig, 8) at which the influence of the hram ring C hecamojwi- ceptible ineream/ with tJu; diameter of the primary riny^ind that them-omlary coil B required to he projected amsidenddy beyond the plane of the primary in order to obtain the maximum effect. Tlie conclusion seemed a natural one that the degree of pro- jection A H of the secondary coil should proportionally increase with the diameter of the primary ring, but the tabu lated figures did not fully justify the inference. Tlie experiments had necessarily occupied a considerable time, and I thought that the difference between the results that shotdd have been observed, accordhig to the above hypoth- esis, and those that were a(;tually ()l>tained, might have been due to the gradual exhaustion of the l>i<:hromate battery em- ployed and to its polarization, although every oare had been taken to preserve its power by removing the carbon and zinc plates from the solution, excepting when an observation was T -•"^--^^ '.•l Mii^llsgiiai PjWWIBg^WWW^i RsttastJM iWiiai9i^%MiM AC iHi mm. n 27 20 2r> IH 2H r 37 14 44 14 A4 Vi 12 IH 23 as 36 lit 39 '22 r>2 18 «8 '20 20 IH 23 >20 ;io lit 39 %\ 53 '20 i 70 16 made. To \mi wluitlmr tho biittory cxortod iiiiy nuiterial inflii- oiicn iipoii tlu Imiirin;; (iistiiiifts u fiirtlicr nerius of nxporiinentH WHS miult! witli \\\v Kiiiiu! !»iittory. It will Ik) rt»;oii \)\ refurouct) to tliu tnlmluteil KtHtoiimnt hIiowii above t! at tlio inaxiiinun heariiijj; (liHtaiu'c H (' had 1k.;)Ii oI»- taiiied with a primary riiij,' ll.;5 cm. in diamoter when the diw- taiire A H lietweeii tii(! |)riiiiarv and Hecoiidary v\nU was ouo (•('titiiiK'trc. This Hrraiijii'iiifiit of the apparatuw was tlierefore adopttnl tliroii^hoiit the foHowiiijj; experiments: MeariiiK diNtunce 1. ApiMinitiiNtrifil with 1 cell. (WchrniimtebivttBry)...(B(!, FiK-H) ^ It uiiii. 2. Six fi'llH in Ht-rifH..... (Hd. Fig-M) =1(> mm. 3. Mix ells in miiltiiilr iirc (BO, FiK.H)= '.» mm. 4. Hix ct'll in two HcricHof 3 eiich (H(!, Fig.H) -= !"> mm. 5. Hiinu' ixiicrimtnt rii«Mktfattery power diil exert an iiitliience npoii lieariti}.^ distance, and also that the battery in nse was irnwhially deteri<)ratinf;. I (•onchided, therefore, that If tlie liattery power had re- mained constant, yKy.tf. the hearing distance ^\^ ^Sf.coruim'y t^ miy-lit not only liave been proportional t<) the diameter of the primary ring, Imt, in order to attain the '<* maximnm effect, the projection of the sec- ondary coil beyond the plane of the pri- mary might also ha\e been found to in- crease in like pro- portion. This led ine to try the effect of a conical primary coil A with the Be(;ondary B at its apex, as shown in Fig. 9, but the hear- ing distance for a bullet was only 3.5 cm. iai lA Siiifiiilurl.v enough Mr. •) . iii lit! Iiad iilttiiiiHMl tit i)iu> tiiiut a hearing (iiHtaiice ol 7.") cm., (or ''\ iiiciinH,' ) liiit In (III H»»iii(' caiiKO not ascertained he was iiiialih! siiiise- i|ii»MitJy to repro- duce the effect. Tlie tiiial foiiii of apparatus adop- ted as the result of ^""■'' the al)ove experi- menttt in Khowii in V\^. 1 1. With this arranjfeineiit ami a l»at- terv of six hichroinate elements freshly set up, we were always sure of a iiearinjjj distance of at least r» cm., although after the battery had lieon in use for some time the hearing distance hurdly exceeded 4 cm. The followin}? are the diinen- iiions of the coils A B (Fig. 11) and their resistance : Coil, A Exteruiil iliiunoter 7 •'"'• luteriml (liiiiueter 4.6 cm. Depth 2.4 cm. Wire used, No. 23, (cotton covered.) ResiBtiince, 2 obms. Coil li Exteruiil iliiiuieter 2-" cm. luteruul diiuiieter ** vaxix. Depth » '"»"• Wire uned, No. 3«, (silk covered.) Kesiotiiiace, 75 ohms. ' See Apjiendix, uote 11. diinetj- 17 Tlu' fii'T of tlin^ iiiiulo hh iicarh' n* poHHiiilc tlin (hiplii-attif* of A aii oUh in three Heries of 2 each. o w o I o o n I II. Series of exj}enm«nt» with a Leclanchi battery of twenty eelln which had bfen net up for about one month, ft had been kept nt/rmally upon open circuit, and had only been occamonally mted. 20 cells in series 20 colls in 10 series of 2 enoh. 20 cells in .5 series of 4 each... 20 cells in 2 series of 10 each. Hearing ilist.ince. 3.3 cnj. 3.6 ja. 4.1 cm, 3.0 cm. Althongh the battery appeared to be in good condition, a close inspection showed that the connections were dirty, and that one of the zinc wires was half broken throngh. ■Hi 18 The defective cell was now removed from tlie cinmit, and tlic coinie(!tion8 of all the other cells cleaned and tighteneparatns re- ) ol)tain the voltaic- l)»'t- nice, a/ul to the request ^^ho had car- passed over but the indi- i. Imagina- lat observed, , ^ W >s ■1 N S s fe s? s :4 ' ii tuKI'-^U HM^iOfl " "~S R a 1 § ? - Vt^tfiy J. TTMf motm Vtf V « \ N \ <0 <0 ' * \ •1 \ «« M 1 * >^ "5" "» «9 20 M but a nuiiiiter (.f experiiiieuts by different observers seemed to indicate that in this ease there was an external cause for the g,,„nth) our apparatus was carried to the Executive Mansion, and an experiment made upon the persoii of the President.^ From some cause then unknown a balance could not be ol>- tained, and the results were therefore uncertain and indefinire. It was discovered afterwards that a mistake had l)een made in the nuKle of (jonnectiug the condenser. The latter should have been connected at E F, (Fig. IJJ,) whereas it was placed at E (t, tlms iutlueucing only one, instead of both, of the primary coils. With the condenser properly ari-anged experiments were tried on July 29 and 80 on three soldiers from the Soldiers' Home who had been wounded during the civil war, namely, John Teahan, Asa Head, and John McGill. In the case of John Teahan no results were ol)tained. In the case of Asa Head, who had a buckshot in the cheek, loud and well-marked sounds were heard in the telephone ; and in the ci;se of John McOill, who was supposed to carry a bullet in his back, no resiilts were obtained. Further efforts were then prosecuted for the improvement of the apparatus. ' See Appoudix, note 12. ' See Appendix, note 13. wm mi! 22 Further K-rperhmnts to Improm Apparatus. Our attention lm, 1881, hear upon the point : Exp. 1. (See Fig. 14.) Eesistance of primary A of ex- ploring instrument, 2 ohms ; resistance of primary C of bal- ancing coils, also 2 ohms ; resistance of exploring secondary B, 140 ohms ; and of balancing secondary D, 120 ohms. Result : Hearing distance of bullet from explorer A B, 3.5 cm. Hearing distance from balancing coils C 1), also 3.5 cm. Exp. 2. (See Fig. 15.) Same exploring coils as in Exp. 1, but balancing coils consisted of a flat primary, E — resistance, 5.30 ohms ; and flat se(!ondary, F— resistance, 83 ohms. The adjustmen' as made by sliding the secondary coil upon the primary until a position of silence was obtained. Result : Hearing distance from explorer A B, 1.5 cm. Hear- ing distance from E F, 3 cm. As a general result of our experiments we found that evertj ipii lipii Hear- 98 increase in the remHtunee of the halamrny cm'fs (especially the pniDarif) reduced tlie Juiariiuj distance of tlta erplorinif instru- rtgM m^M, HUu '> becrtme therefore desirable to do away with this source of resistance as much as possible. Return to Original Foiin of Apparatus. This led us back to the original form of apparatus that had lirst occurred to me, (see Fig. 1,) in whicli a single pair of coils was employed. A few other experiments, made July 29, 1881, will show the imrortance of the point attained. Exp. 3. The two flat coil*:, E F used in experiment 2 were arranged as in Fig. 16, so as to fo'-m a balance by themselves. Result : Hearing distance, 7 en.. In all these experiments the battevy ..^cd consisted of four cells, (Leclanishe.) ng.te. Exp. 4. The same coils used in Exp. 3 were tried again, as shown in Fig. 16, but with a battery of eight cells, (Leclanche.) KM 24 Result; Ilearinji; clistiincie, 8.7 c.in,, or nearly 3^ inches — a result quito unprecedented in our experiments. The foUowinj^ are tlie dinioiisions of the eoils E F: Coll, !■; Extcriml iliiuuot»'r lO cm. Internal iliaineter 2.5 cm. Depth 1 cm. Wire used, No. *i'.\, (silk-covereil.) Coil F Rxternul ilianutcr 10 cm. Internivl (liiimetfr 2.5 cm. Diptli 1 cm. Wire used. No. 28, (mlk-covered.) x r Exi'. 5. The same coils E F, used in E.xps. 'i, B, and 4, were tried once more with a battery of six large bichromate elements, and with a condenser, G, in the primary circuit as shown in Fig. 17. Result : Hearing een aHcertained. In experiments 5, 6, 7, 8, and the suhsequent experiments de- scribed above, the battery employed (ionsisted of six pairs of (!arl»on and zinc, plates of large area placed in a solution of bi- chromate of potash containing sulphuri*^ acdd. The effects noted above were not produced satisfactorily when the battery was much run down, nor were they oi)tained with a Ledanche battery which had l)een set up for soine time, but which appeared to be in good condition. It Itt eiudently neremi/'y in order to produee this eharactcr- idic high tone to use a buttery possesMiu/ coiisideraUe electro- motive force and slight internal resistance. Our experiments had i-eached this stage wlien, on Saturday, the 30th of July, 1881, I was reijuested to make another trial upon the person of the President at the evening dressing of the wound. At this time, however, we had no exploring instruments completed excepting one or two like that shown in Fig. 11 ; for it will be understood that the pi-omising results noted above had been obtained from coils that were simply placed upon a table and adjusted by hand. We immediately proceeded to the Executive Mansion with the apparatus shown in Fig. 13, prepared to make a trial, if it was deemed advisable ; but upon learning of the results of our later experiments the surgeons resolved to postpone any further trial imtil we could arrange the coils (Fig. 17) in a portable form. By forced exertions the c^ils were arranged that same night in a wooden case, as shown in Fig. 18. This ease consisted es- sentially of two oblong blocks A B. A shallow circular recess '•'X^: it'jaa»iiaSi»w^ji»> ! wuWM rf ts waH turned out in each l)lo(^k for the re(!eption of one of the coHh, and flii^ two Mockrt were held together hy four \)\m of elH.iiite, (',!), K, F, wliich paHwed up through Aotn in the upper hhick and were seeured hy eliouite tlunnl)-M'rewK. When the iuHtrunient wan f(>ni|)hited I found to my great diHtrehH that a hahince eouhi not he ohtuined l)y an} adjnst- nieuf of the apparatUH. Tiiere was a position of niininiuni sound, anhtained with tlie same coils hefore the ecuistruetion «)f the wooden case a perfect l»al- aiice and a hearing distance of l'^ em. After numerous unsuccessful experiments had been made to ascertain the cause of the ditticult}' it occurred to Hie that if two adjoining convolutions in (me of tlie (M>ils, made (^mtact at any point, a circuit of low resistance would he formed, (a single ring of wire, in fa(!t,) in which the induced currents might circulate without reaching the telephone connected with the apparatus. I had previously measured the resistancre of the coils without discovering any defect, hut when I considered the large nund)er of convolutions in each coil it seemed possihlc that a defect of this kind nnght exist which couhl not he dis- covered hy a Wheatstone Bridge, excepting hy very delicate and accurate oliservations. To test whether a short-circuited convolution would produce effects analagous to those oi)served, a piece of copper wire was hent into an amndar form and the ends connected together. On hringing this metallic ring near a pail of (mils, (A, B, Fig. 19,) properly adjusted to silence, the halanc^e was loudly disturhed. The copper ring (C) was held as shown in Fig. 19, and the halance could not then l)e re- stored hy any adjustment of the coik. A position of miuimum sound was all that couhl he ohtained, and the hearing distance was enormously reduced. This was prima facie eviden<;e of the nature of the y luuid HH iwnr\y iik poH^iMi- to tln'ptwitiiin of hIUmu'c, 1111(1 tlicii the tliniiil.-8<-n'\vs (', I), K, F w»t." ti^'litciifd. Tlu! Iiiiliinct' iKiw ol.tiiiiuHl WHS not <|iiitt» portWt, lnit l>,y htrikiii" tin- lowi'i- lilock H a f«'W Hiiiurt IdowH with a wo(mIi)H iiiallft wv wvw al»Io to vvAwv tim arruiij;(Miiont to (•oiii|)lotn Hiloiict'. Tlu^ iiiKtrmiU'iit wan thou in siicli a wMihitivo coiKiitioii tliat it could Hcarcd.v Ix- iuovcmI without aft'cctiii^' t\\v l)alan<'«. Hpoii gently swayiiiK it hackwardrt anulging of the thin portion (4 of the wooden cane (Fig. 18) under the weight of the enclosed coil, and tlut simple pressm-e of a finger on thia portion of the case distm-l)ed the balance. The movement of the l(»wer «'oil when the instrument was swayed ahout nnist have heeii ineoTiceivahly small, hut on account of the extreme sensitiveness of the arrangnneoen uiialde to verify this hy a second ohserva- ti(m, altlKMigh the exphtring instriunent (A B, Fig. 13) was repeatedly ])assed over the same place. The sound had heen so loud and well marked that T helieved at the time it nmst have heen (^ansed hy a Budden irregularity in the viliration of the reed of the rheotome used to interrupt the primarj- eircuit, for the arrangement (as explained above, p. 20) was not perfectly balanced, and any irregularity of this kind would, under these circumstances, have aflPccted the tele- phone. At the same time the coincidence was remarkable that the exploring instrument should have been at that very time so near the suspected seat of the ball, and this led to the thought that perhaps after all the l)ullet had been the 1 8ee Appendix, note 15. ' See Appendix, note 14. ■Ml Hi iM ^mi caiiHo of tlu! soniul. I felt (ionfidont that the new instrii- iiieiit (Fig. 18) WMMihl ut once was the only other person present whose ear had been sufficiently Iruiaed to l)e reliable in such an emergency) rrr^^ ■ •--^5■JT^T35-•riT?5■•SS!t^BRWMK■•?^SKKSr■•:■■■ nmmffMtiis^iisiiimes^^iais^xsf mm wa 33 new iuwtni- for tlie ex- 'ig. 13) W!18 van so supe- II due to the llstiii(!t and ''ig. 18) was axcepting a I to and fro. been of ac- Witli tlie ised by the irttninient, I )f the coils) of the Pres- ble the same io simply to I- with equal »f the sonor- le pulsations sity. I was sations were instrument was raised, le area over rying the in- ift"eren(!e be- 16 grew less the two ele- ive been no- ffec^ts, and I et would be ) to imagine eliminating Mr. Sumner hose ear had emergentiy) to repeat tiie experiments and let ine know the result. Upon our return to my laboratory we compared notes, and I found that his observations tallied with mine. lie declared he could not obtain a distinctly localized effect, l»ut stated that he had observed a reinforcement of the pr.lsation over an area of a*^ least two inches in the neigiiborliood of the spot to which his atten- tion had primarily lieen directed, and that he wiS (Minvinced that the bullet was within that area. It appeared reasonaldy cairtain that the area t>f feiible sound was due to some external cause, and was not simply a' effect of expi'c^tancy. In tlie 'absence of any other iipp:\"eiit (^aiise for the phenomenon I was forced to agree in the cionclusion tiuit it was due to the'preseiKie of the bulhit, and I so stated in my report to the Hurge(ms. ' I was by no means satistied^ however, with the results obtained, for no such effects had been observed liefore i'l our experiments with ludletx. I tried to reproduce the effects by moving the instrument (Fig. 18) at different distances over a bullet, I)ut in every case where an effect was produced the soinid was (juite sharply localized. I thought that perhaps the Ixidy of the patient might have af- fected the result, and so experimented upon a ])ullet buried in a piece of meat, but no difference of effect was noted. This led me to fear that the extensive area of feeble sound might have Iteen due to some extensive area of metal that was unsuspected at the time, and I proceeded to the Executive Mansion next morning (August 2) to ascertain from the surgeons whether they were perfectly sure that all metal had been removed from the neighborhood of the oed. It was then recollected that underneath the horse-haii mattress on whicth the President lay was anotiier mattress composed of steel wires. Upon obtaining a duplicate, the mattress was found to con- sist of a sort of net of woven steel wires, witli large meshes. The extent of the sonorous area luiving l)een so small, as com- pared with the area of the bed, it seemed reasonable to con- dude that the steel mattress had produced no detrimental effect.^ • See Appendix, note l(i. " The deivtb of President Giirfield imd the subsecpient poMt-tnorUm exiini- iuatiou, however, proved that the Imllet was ut too greiit a distance from the surface to have affected our appiiratus. 84 I WHS unable to continue exporinientrt with the steel mattress, as just at this time I was obliged to leave Wasliington on account of illness in my family. A.ltliough I was unable for a long time afterwards to carry on personally lndu(!tion Balaiuje ex- periments, the investigations were ably (!ontinue*l under my direction l)y Mr. Tliomas Gleason, in tho establishment of Mr. Charles Williams, Jr., in Boston. Kj^perimentit Conthvue,d in Boston. Mr. Tainter forwarded from Washington drawings of an improved apparatus he had designed to remedy the defects of the instrument shown in Fig. 18, in which the ease, adjusting screws, itc, were all to Ite composed of ebf»nite. Mr. Gloason constructed for me a number of such ebonite <-. struments differing slightly from one another in detail, and tiic apparatus shown in Fig. 20 comltined the different points that had l)een approved. The two (!oils A B were ectcentrically arranged in two cir- cular disks of el)onite, C D, and tiie adjustment was t»btained by means of an ebonite key O, like the key used for tuning pianos, whi(!h turned a cam M pivoted in the upper disk and working in a slot K in the lower di^.k. ill order to prevent any movement of the coils, excepting that produced Ity tlie adjusting-key O, each coil was placed in a recess turned out in its ebonite disk, tlie friges of which were bevelled as shown at R. Paratline was then poured in so jis to fill up eacdi recess. But this alone di-scrow II. Tin's, however, increased the difficMilties of adjustment. When the c-scrow II disturbed wmmmmmm 3S '-liiliiiiiiHMiiiiil^^ 86 the l)aliuuie ; and if tlio 1 1 in ml (-screw H was tightened firwt, then the adjuistnient r.onU only he made l)y a series of jerks, 4m Hwount of friction. In practice we found it l)est to adjust the instrument tiiinost fit KHi'/iif, tmd then the tightening of the thumli-screw II completed the halance. This was the fomi of apparatus ..I whicli we had arrived at the time of the death of President (rartield. The difficulty of adjusting the c<(ils led nie ultimately to the idea of the apparatus shown in Figs. 21, 22, 23, 24, which is the most practical form of the instrument yet devised. Fi^.ai. The two exph)'ing coils A \\ (Fig. 21) are arranged as shown, in a recess turned out in a single block of wood 0. The coils are tempo- rarily connected with a telephone, battery and rheotome in the manner I shown in Fig. 1, so that they may be adjusted by hand to form a balance. When they have been arranged in their posi- ti Ml of silence the hol- low in theldock of wood C (Fig. 21) is filled with melted paraffine. Upon (tooling, the two coils are found im- movably fixed in one solid cake of paraffine. As a matter of practice it is found impossible to fix the c(»il8 in this way exactly in tlieir position of silence ; but by means of two other very small coils, D E, (Fig. 22,) of insignificant resistance, forming a sort of fine adjustment external to the explorer, a perfect l)alance is easily obtained. In this instru- ment the swaying of the coils A B prodnces no offiPict upon the balance. The completed arrangement is shown in plan in Fig. 22, and the explorer and balancing coils are shown separately in perspective iuFigs. 23 and 24. 'W5SS / ' iw^wtsw-ti r aiawi -<'r'?i'isss: lism I I .; »7 MHiiiiillil MiM iiiilMlMMiiii 158 Fiff.ZS. Mi On account of the Kniiill nize and rtli^ht rcHistance of the bal- anciiif,' cotlrt we were enabled to make the adjustable parts of the balancer of metal without practical interference with the sensitivenerts of tlie exploring instvunient, and this gave us the power of making very delicate adjustments of the l)alancing We found it advisable, however, to avoid placing metal over the sensitive area of the coils as had been done in the instrument shown in Fig. '24. In the balancing apparatus Hhown in Fig. 25, (which is the most perfect one yet ,^ of New York, an account of the experiments written by one of the witnesses : " Th£, First Suecessfid Application. " On Friday, Oct. 7, l)y invitation, several medical gentle- " men,^ inclvidiujr the writer, met Prof. Bell at the house of 1 See Mediml GmetU, Oct. 15, 1881, pp. 347-349. 3 ' ' The f ollowdiig are tLe names of the medical gentlemen who were present, " each one of whom verilie 1 perHonally the reHnlts ami declared his entire "'i 1 88 " Dr. Fmnk II. Ilaniilto!!, in tliiw city, for the purpose i»f wit- " iiessiiig the praflical iippli.'dtion of his improved inetniiiient. " Tiie tii'rtt person Hiilijoctcd to experiiueiit was General " Calvin E. Pratt, jiulfjjo of tlie supreme court of the State of " New York, and who is now a resident (tf Brooklyn. Gone- " ral Pratt, at the hattle of Gaines' Mills, June,' 18()2, this ' heing the second day of the famous seven days' retreat across " the peninsula, received a l)all in his left cheek, vvhidi peue- " trated through the luires and was lodged in tiie right antrum. " Its presence at this time was recognized hy his surgictal at- " tendant, Dr. Damainville, and its exact position has lieen " known from that day until this, it having given rise at times " to nmch pain and suffering. " General Pratt has been seen hy Dr. Hamilton and Dr. " Damainville occasionally from that time forward, and they " have from time to time urged upon him the necessity of its " removal. General Pratt, however, was anxious to ktiow " whether Prof. Bell's instrument would indicate its presence " at the same point as declared hy his surgeons. '" The results of the experiment were conclusive and entirely " satisfactory to General Pratt, the response heing heard dis- " tinctly, hut rather feehly, hy every person present in the " room. The feei)lene8s of the pesponse was supposed to he " due to the fac^t that, owing to its situation and the peculiar " form of the instrument containing the induction coils, it was " impossihle to l)ring the centre of its surfatte very near the " site of the hall, the hall heing situated very near the depres- " sion at tlie ala of the nose." " Tlie next patient was Col. 13. F. Clayton, who received a *' wound at the hattle of Cedar Mountain, Virginia, Aug. 9, " 1862. " Tiie missile was supposed to he an P^nlield rifle hall, and " tiie wound was supposed to he mortal isy tlie medical director " of General Banks' staff and his assistants. The l)all passed " through the sternal end of tli^ left clavicle, and was supposed " to have lodged in the muscles under the superior angle of the " corresponding scapula. Tlie injury was followed hy complete " paralysis of the left arm, continuing for a period of six months ; " and his arm has never yet been i fintii- " Imis een troulded occasionally ever since the " injury witli couf:;h, expectoration, and violent palpitations of " the heart. A suspicion has evcMi lieen entertained that the " fistidous canal wiiich remained open a period of eif^hteen " months, and then laicame ])crmanently closed, connuunicated " with tlie hronchial tubes, liut at no time was a suspicion en- " tertaiued Ity him or his medi(;al atU'ndants that the l>all was " jutt lod«j;ed in the !»ack and there closely encysted. " We are disposed to mention as an evidence of (Jul. Clay- " ton's loyalty and faithfulness as a soldier that within six " months of the rec^eipt of the injury, and while the wound was " still discharj^ing pus and Idood, he returned to active duty " with his regiment . nd remained in the field until the close of " the war. " In the presence of the gentlemen assemhled Col. Clayton " exposed his chest, and Prof. Hell proceeded to move the coils " across that portion of his Itack where the ball was supposed " to lie situated, the coUinel indicating the point underneath " the superior angle of the scapula as tiiat which had been fixed " upon by himself and all the surgeons who had examined him " as its exact seat. Although being i)uried underneath the " scapida, they had not been able to verify their diagnosis by " the sense t>f tou('h. Kepeated examiiuitions were made over " this region without any response both by Prof. Bell and sev- " eral of the gentlemen who were present. " The instrument was then moved in every direction across " the bang sincie " (dosed, had evacuated itself, and in a direct line from this " cicatrix towards the left shoulder, which indic^ated the line of " the track of the original sinus." Experiments with Needles. During my al)sence from Washington and from all conven- iences for experimenting personally with Induction Balance apparatus, I devised a method of verifying the indications of IM 48 f,n% r i m tho Iitductinii l^ilanco hikI of jwcortuiiiiiif; tlus oxiitit dt^pth at wliifli a Inillft li(is litMinatli llu^ Kiirfacu. Tliis iimtliofl was cinn- iiuiiiicatt'd tlir()iit;li Dr. Wood ward to tlu; isiir^foiiK in attend- ance oil President (tartield, and it was iiiamw ' iweUr-M ' ^i^w^^*i>mmi!m^ ^m 48 thoii^li from (HTtriiii indicHtioiiH iipptirtMit to tlitt koiiho of toiirli liu Itcliovud tliiit tlio l)ullut vvHrt Im-atiul in tliu|)urt of tliu ImhI^ Buhiiiitted to o.\|)(M-iiii(Uit. To v(^rifv hi«Hiipp(mition n muddle (^oiinwrtod iisuhovofFlf^. 2S) WHS tlinist into (toiituct with tim iiiinl siilistuiicti peirtiivnd, hut no rcHponso was timdo hy thi; tt'leplione. Tho nnrgeon, how- 'ever, lii'lieving that tho hullet liad hettn found, othtjrizud his patient and procfoedeil witii an operation, i>nt dineovered, w hen too hite, that the bullet was not there. FiiHlter hfoil'ifi'dtionx of Imhutiou liidance. I Hailed for Europe early in ()(!toi>er, 18H1, and have had no opportunity since of <'ontininng mj researches until (juite re- cently. While r was in Eiu'ope, however, Mr. Sunnier Tainter devised a new kind of Induction Balance which deserves nien- F iff. 20. tion here. The results olitained with this apparatus in its pres- ent form (Fig. 29) are not to he compared with those produced by the best instnnnents described above, but there are undoubt- edly great po,ssil)ilities of future development. p u 44 Tli*> iiiipiirtiuit fttiiiiii'i! \x tliiit tlu> r.\[ili>i'iiig iiiHtniiiiuiit K (M»iini«t« of ft Hhiijle roll, kd that tliere in no j>os8il)ility of any part of tlin exploror ^ottiii}^ out of iidjiistiiu'iit. All tin* ad- jiistinutits arc mado upon tlm stafiotiarv part of flu- a])paratiitt. Till' curnMit of till' liattiTV in (lividml l>i'twi'oii two i'(|ual c.ir- (MiitH. One of the i)rimarv circiiitH coiitains tlic im>11 A and tlio t'xploriii;; foil K, and this otiirr ciiout tlit) (^)il C and a riii'ostat U. Coils A and (' aro exactly similar; anti(r lialance ran Iid ohtainod l»y the ad- justnii'iit of the secondary coils }{ I) upon the primaries A C ; liiit if the resistance introduced at U is ilitTerent from that at K, Mr. Taintcr states that no lialance is possilde. When till' i])paratus is adjusted to silence the ai)f)roach of a liullet to the vAn\ E destroys the halance. Althoujjh the j;reat oliject of the researches that have been liroujjjlit itefore you to-day luw been to find that arrangement of halance which will ove lead gives the poorest effect of all metals. If people would only make their ludlets of silver or iron there would be no dithculty in finding them in any part of the body ! In the apparatus shown in Fig. JM, however, it seems (uf.lesH subsequent experiments sliould reveal some fallacy) that we have an arrangement which is seiisiti\e to lead and not to iron, oi-, at all events, which is more markedly intluenced by lead than iron. It is hardly necessary to state that when tlie coil C was re- moved to a considerable distance from the primary A "" effect was produced l>y the approach of metal to the coil C. I have in this paper brought before you an outline of a labor of love pursued through mai>y anxious days aiul sleepless nights. However imperfect or disappointing may be the results so far achieved, they are sutticiently encouraging to enalde us to look forward witii confidence to the attainment of still greater perfection. I hope to contimie these researches in the future ; and cer- tainly no man can have a higher incentive to renewed exertion than the hope of relieving suffering and saving life. m L,^*iv> ■h^^^:})f- Vif:^ 3ry 8traiijj;e n A and C tlie field of •ae that the the (!oil C 1 telephone )le disturb- d produced e of a tele- t the sound leaden disk, let, dibturh- ! that in all id gives the ' make their y in finding 8 shown in experiments jTuent which its, which is il C was re- inary A '^" he (;oil C. ne of a labor jpless nights. 18 results 80 enable us to still greater re ; and cer- wod exertion fe. APPENDIX Note 1.— Another mode of painlesH explorntion snggestetl itself to my mind at this time, bused updu the fact that a leaden bullet is much more opa(iue to light than the substani'tis composing the Iniiuiiu body. I was aware of the fact that the ingenious M. Trouvce, of Paris, had, by means of his polyscope, jffoduced a light inside a living llsh, and was thus enabled in the f this apparatus for the illumination of the interior of the human stomach, and I understood him to say that when the instrument was used the body of the ))atient (!ould be seen in the dark, faintly ilhiminated, like a Chinese lantern, and that the extent and location of tumors in the stomach could be detected (m account of their great ojiacity. It occurred to me that leaden ))ullet8 were certainly more opaque than tumors, and that a jjainless method of exploration might be based upon the observations of M. Trouvie. It would evidently be impracticable, in the great majority of cases, to introduce into the Htomach any illuminating apparatus ; but if the light of a projierly prote(!ted incandescent platinum spiral, introduced into the stom- ach, could ))rodnce efifeets visible from the outside— that is, if this feeble light could penetrate through the Rubstance of one-half of the body— then why should not the intense light of an electric arc, or of a lime light, pene- trate the whole body from one side to the other so as to produce similar effects? The most feasible plan that occurred to me v.'ns to place an electric lamp at one end vi a long opaque tnV)e, and to apply the other end closely against tlw skin of the jiatieut. The interior of the t)ibe between two plate-glass diai)hrrtgm8 could be filled with a saturated solnticm of alum, or some f)ther higlily-absorbent transparent substance, so as to obstruct the passage of heat rays. Of course, the whole ai)paratns was to be so arranged that no light from the lamp could escape into the room to interfere with the experiment. Under these circumstances, the body of the patient, or at least a portion of it, should, in a dark room, ai)pear self-luminous; and it seemed i>t)ssible that the shad(,w of au imbedded bullet might be projected up(m the skin. The track of the bullet might also, perhaps, be discernible as an illuminated streak either more or less bright thai\ the surrounding surface. These consideratitms led me to try i). number of experiments, which proved that the method was feasible where the bullet was very near the surface of the body. On account of the great and irregular refraction of light in jiass- ing through the tissues of the body, I doubt whether the shadow of a 47 •M 48 Io upon the Hkiii, uiiIchh, iiiilcfil, u vt'ry lirilliuiit liKht <>munutiu){ from ii Hinglu poiut could be Hitfuly ])roduct'd iimidti the body, The following <'X|)('rim('iitH ("iiriiiK ujjoii thr Hubjfct were umdc in KuHton July fith, IMHI, with the iiKHiHt iiicc of Mr. Wni. Schuyh r JoIiuhoii: Mrprriniint 1. - Mr. JolniMcn pliK^ttd in Iuh mouth n ^Iiihs cylinder ooi>tjv»n- iiiK II H))iriil of |iliitiiiuni wire, which Wiis rendered inciiudeHCcnt by th'' piiHS- iif{(' of III) electrical current. He also held in his cheek ii HiiiiiU leiiden bullet. In II diirk room the eflfect was very striking. The cheek u|)j)eiire mm. in diameter) was attuclied to the glass cylinder by a few turns of black thread jiassed round the cylinder. In this case the effect, although not so marked as in the former experiment, was cpiite discernible, and a faint shadowy streak could be seen crossing tho cheek, caused by the Hhnthiw of the bhick thread tied rouut ui)ou President (lartield's life and the present condition of the sufferer have called forth the nation's deepest sympathies, iiud elicited very many suggestions as to the metlnxls of promoting his comfort and assur- ing his recovery. As one crisis aft<'r another has jmssed ho))e has risen, and the people wait with earnest desire for the last danger to pass away. The attending and consulting surgeons state that it is impossible to predict he final res\ilt of the shot without locating the ball. With all deference to the several methods proposed, I desire to suggest a method of ascertaining the position of the missile which will be painless and harmless, aiid which, in my experiments under conditions analagous to those under wliich it might be practised in the ))resent instance, has proved suc- cessfiil. I rt I'er to the use of the Induction Balance— a most delicate elec- trical instrument for detecting the presence of m.tnls —a modified fonu of which coidd be easily ajjplied in this case with a reasonable expectation of success. This instrument ccmsists of two short glass cylinders, around each of which are wound two parallel coils of tine insulated cojiper wire. One coil of each pair is included in a battery circuit, in which there is .i clock micro])hone. The other p.iiir is placed in a closed circuit with a receiv- ing teleiihoue. The two gloss cylinders, with their encircling coils, may be widely sf^parated. The induction set up in the secondary or telephone circuit is balonced by the reversal of one of the r.econdary coils, and so adjusted that the induction mi 49 in, iiulcHS, 1 l)e wifely in H*>8toQ Br contrm- f the J)11H8- Icn bullet, iired seuii- lanee liy a ' f) mm. in ack thread 'xperiment, Tossing the yliuder. Jfew York AU. sition ill the nt cou(litii)n ami elicited ft uud ttBsur- people wait rle to predict to suggest a painless and j[ous tt> those proved snc- lelicate elec- ifled form of xjjectfttion of around each ,iri'. ch there is a with a receiv- coils, may be ) balanced by the induction in one of the seoondary coils exactly balanfjes or neutralizes the induction in the other, so that when the ^ar is applied to the receiving telephone no sound is *eard. Now, by placing ever so small a piece of met4il in one ;»f the glass cylinders, the electrical balance is disturbed and the clock ou the microphone is heard to tick loudly, thus indicating the presence of metal, and the siuue is true if the coil be placed in the vicinity of a piece of metal. It occurred to me to try the effect of a lead bullet upon the instrument, placing it at different distances, and separating it from the coil by insulating material. The result exceeded my anticipations, as with o set of coils that were by no means sensitive I vim able to locate the bullet with the coils raised a vertical distance of nearly two inches. With more sensitive apparatus it is more than probable that the bullet might be located, even though distant several inches, by passing a pair of coils over the President's back and abdo- men ; and by comparative tests the depth of the bullet might be ascertained. GEORGE M. HOPKINS. Brooklyn, July 10, 1881. Note ^.—Letter from Mr. G. M. Hopkim to Private Secretarj/ Brown, en- ehmiig printed deiuiription of Hugheif Induction, Balance. Office of the Scientific Amebican, No. 37 Park Row, New York, July IIW, 1881. Mr. J. Stanley Brown, Executive Manxion, Washington, D. C: My Dear Sib : I send herewith a full description of the Induction Balance as promised in my note of yesterday. I will send the appnritws for trial if desired. I am certain that the bullet can be located with it if it ih not too deeply seated. Please advise Dr. Bliss. Very respectfully, GEO. AI. HOPKINS, Of the Seientijic A 'nrriean. Note 4:.— Letter from Mr. Oe/). M. Hopkim to Private Secretary Brown ae- companyiug the Hughes' Induction Balance apparatus he fmearded to the Executive Mansion for trial. CO Irving Place, July lUh, 1881. Mr. J. Stanley Brown : Dear Sir : I give beh)w a few suggestions in regard to the use of the In- duction Balance sent herewith. Very respectfully, GEO. M. HOPKINS. Suggestions : Connect A to A, B to B, Ac. , as marked on the wires. Strength of current used, 15 or 20 volts. A strong current extends the influence. Use the clock interrupter, and place a drop of mercury in the vulcanite cup to make connection. WtHtlliMiiimmk 50 The coilH lire uow ftrljnsted to "silence," but will probably have to be re- rtdj-istod ..11 their arrival iu Washington; as a iJ„ inch movement of one of the coils %vill throw it out of aajustment, it will be seen that the adjustment is a matter of great nicety. Tw(» telephone receivers should be employed, and the most acute sense of hearing is roquired to distinguish the ticking when the ball is two inches distant from the coils. Tlie shorter instrument is intended for application to the patient should it be considered suffieieutlv sensitive to warrant the experiment. Asa prelhni'W.-,' experiment pass the Induction Balance over the pocket containing coins, "keys, &c.; also over buttons, buckles, &c., attached to the garments. , Lead is the poorest of all metals to locate with this instrument. If the ball were of iron it could be readily found at a distance of 3 or 4 inches. ■ Yifym 5.— Telegram fro7n Prof. Neiwnnb. • Executive Mansion, Washinqton, D. 0.,Jidy VMh, 1881. To Prof. A. G. Hell, Care of Chan. Williams, 109 Cmirt nt, Jionton, Mam.: Perhaps smtiU core for coil no larger than bullet, with very flue wire, mi^ht give best effect. Shall telegraph to Rowland to know best theoretical form. Telegraph me or Brown, care Executive Mansion, what train >'""/"'',''• Note Q.— Telegram from Prof John TrowMd^e. Bar Habbor, Maine, Jiili/ Idth. To Secretary Brown, White Home. Waxhington,, D. C.,for Prof Bell: Make resistance of secondary coils equal to telephone. Put large number of turns of wire on primary and secondary coils. Primary coils long com- oared with width. Put secondary coils aroui j. middle of primary coils. ^ . , JOHN TROWBBIDGE. Note 1. -Telegram and letter from Prof Rowland U> Prof Neweomb. Hunter, N. Y.. July Uth, 1881. To Prof. Simon Newcomb, Executive Manxion, Washington, D. C: Telegram just received. Mak. ...res four inches long, with six layers of number twentv wire; diameter an inch and one-half. Make outer coil half an inch wide aud half an inch thick, of ftuest wire, and slip over inner coil at its end. jj f^ ROWLAND. ■ ' Letter following above telegram. Hunter, July 14, '81. ^ DEAH^Sw°*When your telegram arrived I had gone to the Hotel Kaaters- kiU. about ten miles from here, to stay over „ ;Ut. The telegram was sent 61 back to the office to be seut to me, and luy friniKls thotight that I hiid received it ; but the stupid luiin here Biinply kept it uud would not send it, becnuse lie had no authority to send it further. I have telegraphed back a reply. The dimensiouH should probably be about as follows : Six Itxtferm t^Xo. £0»oirB . --4tne?i0a- ^ ■J- ^ftc/t, square-. Of course, the two must be precisely alike, and the induction coefficients of one should be made t« vary by ri screw, which would move one of the sec- ondary coils nearer to or further from the end of the primary. Yours truly, • HENKY A. ROWLAND. P. 8. — For these dimeusions a telephone with many turns of fine wire in its coil would be best. Note 8. — Comviunicatwrm with Prof. I). E. Hughes, of London, England, (a.) Cablfgram to Mr. Preeee, Superintendent Postal Telegraph, London, England. Washington, July 15M, 1881. To Prkece, London: y*r ^"^ Can Hughes suggest form of Induction Balance to locate leaden bullet in President ? If bo, cable at my expense, GRAHAM BELL. mmmtm MaiAaaMMM4MiMtd=? ' ■ i^r Y-^fl f^^lrif-' •; 54 Note \Vt.—N»U frmn l>r. Vhif,he»ter A. Btll. N Y CkNTBAL U. It., BETWEEN aVBAOUBB AND BCFFALO, July 16W, 1881. Dear A « B.-. If your coilH are syiumetrioally iirrunged, should it not be posHible to bulauc. the effcet of a bullet on one side by a bullet placed m 5 correBponding iwsitiou on the other? Probably you have thought of this before, but, if not, it may be worth a three-cent stamp. Youth, tnxly, CHICHESTER A. BELL. Note W.—Note and telegram from Mr. J. H. C. Watt*. Balto., July 21#<, 1881. Prof. A. Graham Bew., 1221 Conn. Ave., Waxfiingtim. D. C: Am working hard at our problem. Hucoeeded in reaching full three inches last night, but owiTig. I think, to my battery weakening somewhat, can hardly reach so far now. V.n't you please advise me how you are getting along, and oblige, , Yours, very truly. j. h. C. WATTS. f Telegram. Baltimobe, July 23d, 1881. Prof. A. G. Beli-, WanMngton, D. C: Have been umible to obtain satisfactory results since first trial, and prob- ably yours is at least as good as mine. j H. 0. WATTS. Note n.— Letter to Dr. Bli»». VoLTA Labobatobt, 1221 CoNNEcnctrr aventje, Washington, D. C, July 23, 1881. Db. Buss, Executive Mandon : My Dear Sir : You were kind encmgh to suggest that preliminary experi- ment« should be made with the Induction Balance upon the person of Lieu- tenant Simpson, whose address you gave me. I accordingly communicated with the lieutenant, and he came to my laboratory hvst night in company with Dr. Stanton. The new instruments we had hoped to use were not complete, so we had to content ourselves with the apparatus you tested the other day. Upon passing the coils over the back of the lieutenant, it was found that at one spot a feeble sound made its appearance-too feeble, however, to be entirely satisfactory as evidence of the presence of a ball. I find that very feeble sounds Uke that heard are easily conjured up by imagination and expe to an external cause — probably to the presence of a very deeply-im- bedded Imllet : 1. The Hound, although it could not always be dinting uished, uniformly appeared, when audible, at tlte name uptit. 2. It was heard independently by Mr. Tainter, Dr. Stanton, and myself at the same spot. (If I recollect rightly, the lieutenant himself also located the sound, but iiiy father could hear nothing.) 3. A blindfold test was then made. Mr. Tainter closed his eyes and turned away while the coils were moved over different parts of the lieutenant's back. The moment the sonorous spot was covered Mr. Tainter declared he could hear the sound. We are to rejjeat the ex]>eriments with our new instrumentB as soon as they are completed, and I shall report progress. Yours, truly, ALEXANDER GKAHAM BELL. Note 13.— Letter to Dr. BUm. Wa8hinoto:j, ./«iy 27«A, 1881. Dr. Bliss: My Dear 8ib : Permit me to make a few remarks upon the value cI the indications of the Induction Balance in determining the location of a lead bullet imbedded in the human body. Podtive deduction* eoneeming the lor/ition of the ball can only he mifely made from positive indieMi^in^ of itn pre»enM. Negative indication* may tnean anything. For instance : If we hear a sound from the telejihone connected with the balance every time the exploring coil is passed over a certain part of the body, this may b»i taken ns proof positive that a metallic mass is to be found in the neighborhood of the sonorous spot. If, on the other hand, we fail to obtain audible effects, we are not entitled to conclude that the bullet is absent from the part explored, or that it is imbedded ut a greater distance below the surface than the i)enetrating distance of the instrument used, for the bullet may be witliin any part of the area explored and close to the surface without afflicting the balance if it is flattened, and if it is so located that the i)lttne of its face is nearly perpendicular to the plane of the face of the exploring coil. A few words may not be out of place here concerning the experiment made lost night ujion the person of the President. Before entering the President's room, I applied the telephone to my ear, and heard a peculiar spluttering sound which it was found impossible to extinguish by any adjustment of the coils. I satisfied myself, however, that the arrangement was in a sensitive condition, by holding near it a flattened bullet. The hearing distance appeared to be about 4 cm. When the explor- ing coil was passed over the back of the President near the spine, no definite pulsation of the sound was heard ; but when the coil was first passed over a portion of the front part of the abdomen near the right side, I heard at one point a shaqj and sudden reinforcement of the sound. Upon moving the coil backwards and forwards a number of times over the same spot, I was unable to verify the observotiou. I should state here that, when a perfect balance is 5« nut ubtniutui, it in not mifo to plitco reliituco upon a Hingle obsorvfttion of u piilHiition in the sound, iw n Kiuiiliir cffoct might ha eiuiHud hy an aoi-iclcntal irregularity in the vibration of the iuHtrunicut iwed to intemipt the eleotrioal current. The Hoiind heard was dintinct and well marked, but it wotild not be safe to ccmcludo that it was due to the prcr" e of the bullet, unlesH the effect could be rci)roaratus. Yonra, triily, ALEXANDER OUAHAM BELL. Note li.— letter to Dr. Blm. VOLTA LaB0B*TOBY, 1221 CoNNECTnCUT AVENUE, Washimoton. D. C.,July 31, 1881. My Deab Dk. Bliss : I write to let you know that my new form of Induc- tion Balance gives brilliant promise qI success. The indications with a flat- tened bullet are well marked and distinct at a distance of three inches, and audible effects can even be diHtinguished at five inches, but beyond three inches silence and the greatest attention are requisite. Effects are produced at about two inches, when the bullet is held with its edge towards the instru- ment — a position that gave no results with our former apparatus. .Vltogether I feel v(!ry much encouraged. The apparatus in its present form is a very clumsy affair, the surface that would be applied to the person of the President measuring seven inches by four. I hope to reduce the size of the apparatus very greatly in a day or two. In the meivntime, should any neces- sity arise for an experiment upon the President, we have much better chances of success than at any previous time. Yours, very truly, ALEXANDER GRAHAM BELL. vfttion of a 10 (vluctrical t be Wife to affect could >rning that e iimrkedly y about one InHt uight, to out' Hide lunt for the :ouHtic bal- >niniend an ly arranged. :iuld, at all he presence it might be Taiuter and VI BELL. BNUE, '31, 1881. oa of Induc- ) with a flat- iucheii, and Byond three re produced s the instru- iresent form erBon of the 9 size of the 1 any ueoes- tter chances M BELL. 57 Note 16.— /w«<^r t>i Dr. /«»**. VOLTA LaBOHATORV, 1221 (JoNNECnCUT AVKNVK, . Wahhinoton, I>. C, July Ml, 1881. Dr. BuHH, K/ecutirf Mannnn : Dear Hi We have made ex|)eriniPutH this evouing upon the |M>r(ioti of I'rivate .lohu Mcdill, an old solilii^r, who was wonndeil at tlu< battle of Oaiues' Mill, iu 1SG2, and who still carries the ball that shot him. I found no difficulty in flndiug a sonorous spot in his back, when' undoubt- edly tlm bullet lies imbedded. Mr. Taiuter also located the Imllet in the same place. Upon pressing with the flugers uiion the Hi>ot a lnm|> coulil be felt between two of the riVis. We experimented ujMm this same man yestenlay, using a similar form of Induc- tion Balance to that we tried upon the person of thi^ President the other day, but could obtain no indications. The new form of Induction lialance is so sensitive that a new difficulty is intnMluced by the effects produced by large iiietnllic masses— for instinco, gas lustres, iron flre-jjlaces, Ac. I think also that the earth's mivgnetism affects the result. We shall inves- tigate these causes of disturbance to-night. Yours, sincerely, ALEXANDIilt (HtAHAM BELL. Note 16.—Ht>port to the mirgeom publinhed in the daily jtapern Aug. 2, 1881, VoLTA Labobatorv, 1221 (!oNN. Ave., Washington, 1). C, Aug. \»t, 1881. To the Hurgeong in nttendnnee upon Prenident Oarfleld : Gentlemen : I beg to submit for your information a brief statement of the results obtained with the new form of Induction Balance in the experiments made this morning for the purjiose of locating the bullet in the person of the President. The iustrumeit was tested for sensitiveness several times during the course of the experinHsuts, and it was found to respond well to the presen- tation of a flattened bnllei; at a distance of aliout four inches from the coils. When the exploring coils were passed over that part of the abdomen where a sonorous spot was observed in the experinieuts made on July 2(;tli a feeble tone was perceived, but the effect was audible a considerable distance around this spot. The sounds were too feeble to be entirely satisfactory, as I had reason to expect from the extreme sensitiveness of the instrument a much more marked effect. In order to (vscertain whether similar sounds might not be obtained in other localities I explored the whole right side and back below the point of entrance of the bullet, but no part gave indications of the presence of metal, except an area of about two inches in diameter, containing within it the spot previously found to be sonorous. The experiments were repeated by Mr. Tainter, who oVitained exactly corresponding results. We are therefore justified in concluding that the ball is located within the above-named area. In our preliminary experiments we found that a bullet like the one in ques- ^.>«...>„.^.«:.,-,.«.-J.,.i,A-.,^ ^^.-a ..,,„.■.,,),,, ,^.^.^^yi^_-i,. .^-.-^^.■■^_ tioii wht'ii in itM luiniiiil Hhupr prixlucfd noimdiliU' flTect Im^vkuiI u iliHtuncii of twii mill Ik lii.lf iiK'lu'M, while the Hikiiit> Imllft, Hiittfiicd niiil priMciitcd uitli iU fuel' purikllcl Id tlic \i\,nu> iif the c'iiIIh, kuvi' iniliriitioim up tun (1iHt»uc«> of five illcheM. The Hiiliie Hatteiieil hullet, helil with itN fitce per|H'li