SCIENCE AND MAN. 349 



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, how- 

 ever, not only states the principle, but illustrates nu- 

 merically 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 -^ 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 re- 

 stored. 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 moun- 

 tain an amount of heat equal to that produced by the 

 combustion of the foregoing amount of carbon is re- 

 stored. The muscles of a labourer whose weight is 

 150 Ibs. weigh G4 Ibs. When dried they are reduced 

 to 15 Ibs. Were the oxidation corresponding to a day- 

 labourer's ordinary work exerted on the muscles alone, 

 they would be wholly consumed in 80 days. Were the 

 oxidation necessary to sustain the heart's action concen- 

 trated 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 



