THE COPLEY MEDALIST OF 1871. 329 



by the wave-motion of the sun is changed into the rigid 

 form of chemical tension, and thus prepared for future 

 use. With this prevision, as shall subsequently be shown, 

 the existence of the human race itself is inseparably con- 

 nected. It is to be observed that Mayer's utterances are 

 far from being anticipated by vague statements regarding 

 the "stimulus" of light, or regarding coal as " bottled 

 sunlight ." He first saw the full meaning of De Saussure's 

 observation as to the reducing power of the solar rays, and 

 gave that observation its proper place in the doctrine of 

 conservation. In the leaves of a tree, the carbon and 

 oxygen of carbonic acid, and the hydrogen and oxygen of 

 water, are forced asunder at the expense of the sun, and 

 the amount of power thus sacrificed is accurately restored 

 by the combustion of the tree. The heat and work 

 potential in our coal strata are so much strength with- 

 drawn from the sun of former ages. Mayer lays the axe to 

 the root of the notions regarding " vital force "which 

 were prevalent when he wrote. With the plain fact before 

 us that in the absence of the solar rays plants cannot per- 

 form the work of reduction, or generate chemical tensions, 

 it is, he contends, incredible that these tensions should be 

 caused by the mystic play of the vital force. Such an 

 hypothesis would cut off all investigation; it would laud us 

 in a chaos of unbridled fantasy. "I count," he says, 

 " therefore, upon your agreement with me when I state, as 

 an axiomatic truth, that during vital processes the conver- 

 sion only, and never the creation of matter or force 

 occurs." 



Having cleared his way through the vegetable world, as 

 he had previously done through inorganic nature, Mayer 

 passes on to the other organic kingdom. The physical 

 forces collected by plants become the property of animals. 

 Animals consume vegetables, and cause them to reunite 

 with the atmospheric oxygen. Animal heat is thus pro- 

 duced; and not only animal heat, but animal motion. 

 There is no indistinctness about Mayer here; he grasps his 

 subject in all its details, and reduces to figures the con- 

 comitants of muscular action. A bowler who imparts to 

 an 8-lb. ball a velocity of thirty feet, consumes in the act 

 one-tenth of a grain of carbon. A imui weighing 150 Ibs., 

 who lifts his own body to a height of eight feet, consumes 

 in the act one grain of carbon. In climbing a mountain 



