VELOCITY OF TRANSMITTED IMPULSE 139 



experiment the point of application of stimulus was at 

 a distance of 30 mm. ; the total time was found to be 

 1*9 second. In the next experiment the distance was 

 reduced to half, that is to say, 15 mm., and the total time 

 was found to be i second. And lastly, the latent period 

 was determined, under direct stimulation, at -08 second 

 (fig. 83). Thus 



Vj = - — ^-^-^ = 16-4 mm. per second 



^2 = _ ^^ ^ ^^'3 ^^' P^^ second 



V3 = — — = i6-6 mm. per second 



1-9 -I 



Fig, 83. — Determination of velocity by differential method. The records 

 from below to above are in response to stimuli applied at distances 

 of 30 mm., 15 mm., and directly. Recorder lo D.V. 



The three results thus obtained from independent data 

 are here seen to be extremely consistent. They bear very 

 emphatic testimony not only to the accuracy of the method 

 but also to the constancy of the velocity in a given specimen 

 under unvarying external conditions. 



It has been stated that the accuracy of these time- 

 measurements can be pushed to almost any extent. In 

 order to demonstrate this fact, and also to exhibit the high 

 mutual consistency of various determinations, I reproduce 



