with the Induction Balanee. 49 
strument toward the back of the President, the difference be- 
tween the pulsations produced at the two elevations grew less 
and less, and finally could not be distinguished. 
the difference in the loudness of the sound at the two ele- 
vations was so slight that it probably would not have been no- 
our return to my laboratory we compared notes, and I found 
that his observations tallied with mine. He declared he could 
hot obtain a distinctly localized effect, but stated that hehad 
observed a reinforcement of the pulsation over an area of at least 
two inches in the neighborhood of the spot to which his atten- 
tion had primarily been directed, and that he was convinced 
that the bullet was within that area. 
It appeared reasonably certain that the area of feeble sound 
was due to some external cause, and was not simply an effect 
_ Of expectancy. In the absence of any other apparent cause 
was another 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, with large meshes. 
The extent of the sonorous area having been so small, as com- 
pared with the area of the bed, it seemed reasonable to con- 
clude that the steel mattress had produced no detrimental 
AM. Jour. Sct.—Tuirp Series, Vou. XXV, No. 145.— January, 1583 
4 
