APPENDIX I. 123 



processes in the brain, nearly another second will 

 elapse before the order can be telegraphed to the 

 muscles of the tail to capsize the boat. 



Again, suppose the engine-driver on the locomo- 

 tive of an express-train running a mile a minute 

 holds his arm extended towards the tender, and 

 moves his fingers, then the nervous agent in the 

 motor fibres of his arm will rest in space or nearly 

 so, because its motion is destroyed by that of the 

 train, just as a cannon-ball, fired at the equator due 

 west, has its motion destroyed by that of the earth 

 around its axis, and does not strike the wall or the 

 ship's side, but is struck by them. And the same 

 thing will happen with the nervous agent in the 

 sensory fibres of the fireman's arm, if, standing on 

 the tender, he should burn his hand at the loco- 

 motive. 



But also in the racehorse and greyhound, when 

 they are running at full speed, the nervous agent 

 will nearly rest in space, and in the flying eagle it 

 will even be carried in the opposite direction. 



As in these cases the whole body of the animal is 

 darted through space at a rate equal or even superior 

 to that of the nervous agent, it will be less a matter 

 of surprise that a man should be able to move his 

 hand almost as quickly as that agent moves along 

 his nerves. This can be made apparent by the 

 height to which a heavy body, a stone, for instance, 

 may be thrown. Throwing, in fact, is nothing else 

 than imparting the greatest possible velocity to the 

 hand, together with the projectile, and letting this 

 fly when the tangent to the curve, wherein the hand 



