342 KANSAS CITY REVIEW OF SCIENCE. 



the greatest hearing distance to the telephone, to find an instrument which would 

 cause a sound at the greatest distance possible from the induction balance. He 

 tried several experiments to find a solution to this difficulty, and telegraphed for 

 the advice of scientific friends, both in America and England, but was unable to 

 make an instrument which would pronounce an audible sound with the metal 

 bodies sought for, further than one and a half inches from the induction balance. 

 He succeeded in perfecting an instrument which allowed a distance be- 

 tween the metal and the balance of five centimetres. In this instrument the pri- 

 mary coil was of a conical shape and the secondary coil fastened on the apex. 

 A very considerable improvement was discovered soon afterward, when, at 

 the suggestion of Professor Rowland, he applied a condenser in the primary 

 circuit. The result was wonderful. On bringing a bullet near the induc- 

 tor, the telephone emitted a sound resembling a high, shrill whistle ; in fact, 

 the condenser appeared to act as a resonator. It was with the instrument 

 in this condition that he made the first experiment with the late President's 

 wound, the result of which had never been published. The instrument on the 

 occasion was out of order, and emitted an uncertain spluttering sound which 

 they could not stop, and consequently the experiment was a failure. He then 

 turned his attention to another system of induction balance consisting of two 

 roand plates, one placed over the other and in a wooden case It was with this 

 instrument that he made the second experiment with General Garfield on August 

 ist. The trouble with this instrument was that the siightest motion caused a 

 deflection in the plates, giving a continuous sound in the telephone. The instru- 

 ment was so delicate also that the chandeliers and iron fire-place in the room affect- 

 ed it. On passing the instrument over a portion of the body above the thigh a 

 distinct sound was heard, and although the instrument was raised a foot above 

 this area it was affected, although not the same extent as when it was closer to 

 the body. Subsequent events proved that the bullet was not lodged in that area 

 and he could only account for the action of the instrument by the fact that the 

 patient lay on a steel wire bed. The difficulty in the instrument of the move- 

 ment of the plates was effectively removed by imbedding them in a mass of par- 

 affine, and this is the instrument as perfected and with which the bullet was discov- 

 ered in the body of civil war veteran. He was still pursuing his investigations 

 and hoped yet to bring the instrument to a much greater state of efficiency. 



A modification of the instrument, in which the plates were in a hoop large 

 enough to pass over the limbs for determining the location of bullets lodged in 

 the extremities, he exhibited. In concluding, he said that lead was the metal of 

 all for acting with electric apparatus and warmly expressed the wish that in future 

 bullets should be made of silver or iron. His work in this direction had been 

 purely a labor of love, and he could not have had a higher inducement than 

 working to alleviate sufferings. 



