XXI. 



DEATH BY LIGHTNING. 



1 )EOPLE in general imagine, when they think at 

 JL all about the matter, that an impression upon 

 the nerves a blow, for example, or the prick of a pin 

 is felt at the moment it is inflicted. But this is not 

 the case. The seat of sensation being the brain, to it 

 the intelligence of any impression made upon the nerves 

 has to be transmitted before this impression can be- 

 come manifest as consciousness. The transmission, 

 moreover, requires time, and the consequence is, that 

 a wound inflicted on a portion of the body distant from 

 the brain is more tardily appreciated than one inflicted 

 adjacent to the brain. By an extremely ingenious ex- 

 perimental arrangement, Helmholtz has determined 

 the velocity of this nervous transmission, and finds it 

 to be about eighty feet a second, or less than one-thir- 

 teenth of the velocity of sound in air. If therefore, 

 a whale forty feet long were wounded in the tail, it 

 would not be conscious of the injury till half a second 

 after the wound had been inflicted.* But this is not 

 the only ingredient in the delay. There can scarcely 

 be a doubt that to every act of consciousness belongs 

 a determinate molecular arrangement of the brain 



* A most admirable lecture on the velocity of nervous trans- 

 mission has been published by Dr. Du Bois Reymond in the ' Pro- 

 ceedings of the Royal Institution ' for 1866, vol. iv. p. 575. 

 29 439 



