Instruments and Experiments. 



109 



Very many of the experiments before described, may be perform- 

 ed with it. Both this instrument and the double hehx and elec- 

 trotome, readily furnishing a rapid succession of shocks of every 

 degree of intensity, are highly convenient for the medical appli- 

 cation of electricity. 



Fig. 2. 



In September last, J. Smyth Rogers, M. D., of New York, then 

 on a visit to this city, observed a difference in the intensity of the 

 shocks received by the two arms when connected with the cups, 

 S and S, of the separable helices and revolving armature. On 

 his mentioning the circumstance to me, we undertook to verify 



