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Buchanan 



moving plate than are any of the others introduced into this paper. It 

 shows that, when the vibrator of the primary coil was breaking and making 

 a contact 54 times a second, each induction shock was producing a separate 

 excursion of the meniscus, the one in the one direction the other in the 

 other. The break effect was strong (ascent, considering the quick rate of 

 movement of the plate, steep), the make effect was a good deal weaker, but 

 each had the same duration, namely, I'ocr. Between each break and make 

 effect, and again between make and break effect, there was an interval 

 lasting respectively about 6 and 5 times as long as either of the excursions 

 themselves, i.e. about 9a- and Her, during which the meniscus resumed its 

 resting position. I conclude, therefore, that the instrument I have been 

 usins: would be capable of registering as distinct each of a succession of 

 effects produced immediatel}' b}^ instantaneous electrical changes whatever 

 their strength, and wliether all of equal strength or not, provided their 



Fifi. 7. — Diagram showing the effect produced upon the cajiillary electrometer 

 when four make alternating with five break induction shocks were 

 allowed to escape into it. Quick rate of plate, as shown by 100 fork tracing 

 above. 



frequency was below 700 per second. When the effects are not produced 

 immediately by such changes, the highest frequency with which they 

 can appear as distinct depends, of course, also upon the duration of each 

 intermediate electrical change. When the electrical \ariation of the flexor 

 muscle was interposed between the induction shocks and their effects on 

 the electrometer, we may gather from the photographic record reproduced 

 in fig. 6 B that the duration of the muscle effect was becoming shorter 

 and shorter to successive stimuli. To begin with, it outlasted the stimulus 

 producing it by nearly 0"02 second ; before two-tenths of a second were 

 over it was outlasting it by only about O'Ol second, and later by an even 

 somewhat shorter time still ; but whatever it was, the time taken by the 

 instrument remained but a small fraction of it. 



One would like to know, for each of the three string-galvanometers 

 which were used by Piper, the time taken by the " string " (quartz fibre or 

 platinum-tungsten wire) to come to rest, when disturbed by the immediate 

 action upon it of a single induction shock. If we may judge by the escapes 

 which are represented in the records reproduced in his second paper [(2), 



