SCIENCE AND MAN. 607 



men took up this subject subsequently and independently, 

 but all that has been done hitherto enhances instead of 

 diminishing the merits of Dr. Mayer. 



Consider the vigor of his reasoning. "Beyond the 

 power of generating internal heat, the animal organism 

 can generate heat external to itself. A blacksmith by 

 hammering can warm a nail, and a savage by friction can 

 heat wood to its point of ignition. Unless, then, we 

 abandon the physiological axiom that the animal body 

 cannot create heat out of nothing, we are driven to the 

 conclusion that it is the total heat, within and without, 

 that ought to be regarded as the real calorific effect of the 

 oxidation within the body." Mayer, however, not only 

 states the principle, but illustrates numerically the transfer 

 of muscular heat to external space. A bowler who imparts 

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

 one-tenth of a grain of carbon. The heat of the muscle is 

 here distributed over the track of the ball, being developed 

 there by mechanical friction. A man weighing 150 Ibs. 

 consumes 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 com- 

 bustion 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 sustain 

 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 consume the 

 associated muscular tissue in 3-J days. With a fullness and 

 precision of which this is but a sample did Mayer, between 

 1842 and 1845, deal with the great question of vital 

 dynamics. 



In direct opposition, moreover, to the foremost scientific 

 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 previously 



