Upon the electrical experiments to determine the location of the bullet in the body of the late President Garfield; and upon a successful form of induction balance for the painless detection of metallic masses in the human body . )laced upon ataltle and adjusted by hand. We immediately proceeded to the Executive Mansion withthe apparatus shown in Fig. 13, prepared to make a trial, if itwas deemed advisable ; but upon learning of the results of ourlater experiments the surgeons resolved to postpone any furtliertrial until we could arrange the coils (Fig. 17) in a portal)leform. By forced exerti
Upon the electrical experiments to determine the location of the bullet in the body of the late President Garfield; and upon a successful form of induction balance for the painless detection of metallic masses in the human body . )laced upon ataltle and adjusted by hand. We immediately proceeded to the Executive Mansion withthe apparatus shown in Fig. 13, prepared to make a trial, if itwas deemed advisable ; but upon learning of the results of ourlater experiments the surgeons resolved to postpone any furtliertrial until we could arrange the coils (Fig. 17) in a portal)leform. By forced exertions the coils were arranged that same nightin a wooden case, as shown in Fig. 18. This case consisted es-sentiallv of two oblonuIjlocks A B. A shallow circular recess. 28 was turned out in eacli ])lock for tlie reception of one of thecoils, and the two blocks were held together by four pins ofel)onite, C, D, E, F, which passed up through slots in the upperblock and were secuied by ebonite thunil)-screws. When the instrument was completed I found to my greatdistress that a balance could not be obtained by any adjust-ment of the apparatus. There was a position of mininnnnsound, and the telephone responded to a bullet presented to thecentral partG of the instjument; but the hearing distance didnot exceed 3 or 4 cm., whereas we had obtained witli the samecoils before the construction of the wooden case a perfect bal-ance and a hearing distance of 13 cm. After numerous unsuccessful experiments liad been made toascertaiii the cause of the difficulty it occurred to me that iftwo adjoining convolutions in one of the coils, made contactat any point, a ciicuit of low i-esistance would l»e formed, (asingle ring of wii-e, in fact,) in which the induced current
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