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 % 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 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 
