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



was then allowed to cool to its old temperature, when a second series 

 of responses were taken, the stimulus intensity being the same as 

 before. It will be seen how the responses are enhanced by annealing. 



Before After 



Fig. 6. — Series of responses, to uniform stimuli, of both A and B wires, before and 



after annealing. 



Effect of Previous Vibration. — The increased sensitiveness conferred by 

 previous vibration has already been referred to before. I give below 

 a record (fig. 7) obtained with platinum (I have obtained similar 



(a) <b) (o 



Fig. 7. — Photographic record showing the effect of continuous stimulation in 

 enhancing response (Pt). Each curve shows response (followed by recovery), 

 the stimulus being kept constant throughout. The series of responses (a) r 

 enhanced to series (c) after continuous vibration (b). 



records with other metals), which clearly shows how the response is 

 enhanced after preliminary vibration. 



Sometimes the wire gets into a very sluggish condition, when the 

 response almost disappears ; in other words, owing to some molecular 

 modification, responsiveness is reduced from the normal positive value 

 (by positive is meant that the acted wire becomes zinc-like or is 

 zincoid) to zero. In these cases annealing or preliminary vibration 

 are usually effective in transforming the sensitiveness from zero to a 

 positive value. 



