122 APPENDIX I. 



VELOCITY OF Metres in one second. 



Cannon-ball .... 552* 



Wind 120 



Eagle's flight .... 35f 



Locomotive . . 27 



Greyhound, Racehorse ... 25 



Nervous Agent .... 2630 



Hand throwing stone 24m '5 high . 21 '9 



Muscular contraction ... 8 1 2 



Arterial wave , . . . 9*25 



Blood in dog's carotid . . . 0'2 0'3 



capillaries . . . 0-00060-0009 



Particles moved by cilia . . 0-00007 



A glance at this table shows that the velocity of 

 the nervous agent, far from being enormously great, 

 as most physiologists formerly supposed, is, on the 

 contrary, wonderfully small. Not only is it beyond 

 any comparison smaller than the velocity of elec- 

 tricity and light, and the so-called planetary veloci- 

 ties, but it is even small when compared to the 

 velocity of sound in different media, or to the initial 

 velocity of a cannon-ball. 



In order better to realize how slowly sensation 

 and volition are transmitted through the nerves, let 

 us suppose that a large whale, which may be thirty 

 metres long (98J feet), has its tail struck by a 

 harpoon. It will then take about one whole second 

 before the pain reaches the huge creature's brain ; 

 and, neglecting even the time required for the 



* Rev. Samuel Haughton, in the Proceedings of the Eoyal 

 Irish Academy, 1862, vol. viii., p. 113. 



t Simmler, Poggendor/'s Annalen, u. s. ic., 1864. Bd. cxxi., 

 S. 331. 



