SCIENCE AND MAN 367 



velocity of 30 feet to an 8-lb. ball consumes in the act jV 

 of a grain of carbon. The heat of the muscle is here dis- 

 tributed over the track of the ball, being developed there 

 by mechanical friction. A man weighing 150 Ibs. con- 

 sumes in lifting his own body to a height of 8 feet the 

 heat of a grain of carbon. Jumping from this height the 

 heat is restored. The consumption of 2 oz. 4 drs. 20 grs. 

 of carbon would place the same man on the summit of a 

 mountain 10,000 feet high. In descending the mountain 

 an amount of heat equal to that produced by the combus- 

 tion of the foregoing amount of carbon is restored. The 

 muscles of a laborer whose weight is 150 Ibs. weigh 64 

 Ibs. "When dried they are reduced to 15 Ibs. Were the 

 oxidation corresponding to a day- laborer's ordinary work 

 exerted on the muscles alone, they would be wholly con- 

 sumed in 80 days. Were the oxidation necessary to sus- 

 tain the heart's action concentrated on the heart itself, it 

 would be consumed in 8 days. And if we confine our 

 attention to the two ventricles, their action would con- 

 sume the associated muscular tissue in 3% days. With a 

 fulness and precision of which this is but a sample did 

 Mayer, between 1842 and 1845, deal with lite great ques- 

 tion of vital dynamics. 



In direct opposition, moreover, to the foremost scien- 

 tific authorities of that day, with Liebig at their head, 

 this solitary Heilbronn worker was led by his calculations 

 to maintain that the muscles, in the main, played the part 

 of machinery, converting the fat, which had been previ- 

 ously considered a mere heat-producer, into the motive 

 power of the organism. Mayer's prevision has been jus- 

 tified by events, for the scientific world is now upon his 

 side. 



