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Prof. J. C. Bose. On Electromotive Wave [May 21, 



negative, is sometimes modified by the molecular condition of the wire 

 (see below). In the modified form of apparatus the wires in the cell 

 ,are immersed to a definite depth in the electrolyte ; there is thus a 

 perfect and invariable contact between the wire and the electrolyte. 

 The wire in the cell is clamped below, and torsional vibration gives rise 

 to a strong electrical response. If the wire be now carefully un- 

 damped, and the vibration repeated as before, there will now be found 

 no electrical effect. As all the rest of the circuit was kept absolutely 

 the same in the two different sets of experiments, these results conclu- 

 sively prove that the responsive electromotive variation is solely due to 

 the mechanical stimulation of the acted wire. The excitatory effect 

 due to the disturbance persists for a time. This may be shown by 

 keeping the galvanometer circuit open during the application of vibra- 

 tion, and completing it at various short intervals after the cessation, 

 when a persisting electrical effect diminishing rapidly with time will be 

 observed. When the wire is brought to the normal condition, succes- 

 sive responses to uniform stimuli are, in the case of metals which, like 

 tin, show no fatigue, exactly the same. I usually interpose a high 

 external resistance, varying from 1 to 5 megohms, so that the galvano- 

 meter deflections may be proportional to the electromotive variations : 



