RAPIDITY OF THOUGHT. 55 



difference has been recognised in various ways, and is shown 

 in the difference of what is termed ' personal equation ' of 

 astronomical observers, no two of which are found to record 

 the occurrence of a given phenomena at exactly the same 

 instant of time, but differ in the period of record from the 

 exact time by a definite amount. Basing his conside- 

 rations upon observations of phenomena of this kind, 

 F. Gralton, in an address before the British Association, 

 at Plymouth, says : ' The very foundation of the difference 

 between the mental qualities of man and man admits of 

 being gauged by a scale of inches and a clock ; ' 1 and pro- 

 poses to measure by these means the difference of rate of 

 nervous transmission in persons of different temperament ; 

 also the time occupied in forming an elementary judg- 

 ment : and suggests experiments and methods, by means 

 of which the mental faculties of different persons might be 

 measured. That there is great room for original investi- 

 gation and discovery in this direction appears certain ; and 

 it is to be hoped that the subject will soon be experimen- 

 tally investigated. 2 



Many experiments have already been made, chiefly by 

 German investigators, on the speed of nervous transmis- 

 sion. According to Block, the c rapidity of the nerve 

 current in the spinal cord is 1 94 metres per second ; in the 

 nerves 133 metres per second;' other experimentalists had 

 previously found lower rates of rapidity of the current in 

 sensory nerves, viz. ; ' 94 metres per second (Kohlrausch), 

 60 (Helmholtz), 41-3 (Von Wittich), 34 (Hirsch), 30 

 (Schelske), and 26 (De Jaager).' 3 And Professor Bonders, 

 of Utrecht, has invented what he terms a Noematacho- 



1 Athenaium, Aug. 25, 1877, p. 242. 



2 See Athenceum, Oct. 25, 1877, p. 242. 



3 Mind, vol. i. p. 133. 



