BOYLE, HOOKE, AND MAYO. 493 



varies inversely as the squares of the distance, 

 he would not have referred their lasting motions 

 to a single impulse, exerted through a vacuum. 

 Or had he known that the quantity of life di- 

 minishes from the equator to the polar regions, 

 like all the mechanico-chemical transformations 

 of matter, he would not have regarded comets as 

 destined to supply the planets with vitality. But 

 as he confounded the cause of motion, of climate, 

 changes of season, the growth of vegetation, &c. 

 with vibrations of an aether which he never iden- 

 tified with any known agent, it is not very sur- 

 prising that his physical speculations have been 

 little understood. 



During the time of Newton, it was discovered 

 by the experiments of Boyle, Hooke, Mayo, 

 Bathurst, and Henshaw, that, during the process 

 of respiration, a portion of atmospheric air un- 

 derwent the same change as in ordinary combus- 

 tion ; by which its elasticity was greatly dimi- 

 nished, and its property of supporting life de- 

 stroyed. Mayo supposed that a nitro aerial spirit 

 was imparted to the blood in the lungs. But in 

 accordance with the reigning fashion of the day, 

 animal heat was referred to innate powers of the 

 system, or to motion of the blood, its friction, 

 against the solids, &c. 



From the times of Homer, Hippocrates, Galen, 

 and Celsus, down to the period of Harvey and 

 Sydenham, the animating principle was sup- 



