Page:Life in Motion.djvu/170

150 fifteen grains lifted a height of twelve feet. This may seem a small amount of work, and it would be so if, in doing it, the gramme of muscle disappeared; but only an infinitesimal part of the muscle-substance is used up in the experiment, and the most careful weighing would probably fail in detecting the loss. Perhaps not more than the one-thousandth part of the fifteen grains of muscle has been used to lift that weight twelve feet high.

Chauveau, one of the greatest of living French physiologists, has recently reinvestigated the question by ingenious experiments on the muscles of living men in normal conditions. These experiments oblige Chauveau to reduce Fick's estimate and to give the total effective energy as only from twelve to fifteen per cent. Taking the total mechanical energy of a man instead of a muscle, some recent calculations of my own show an output of mechanical energy as a little over seventeen per cent.

It is evident, therefore, that, considered as an engine, a muscle is not much better as a transformer of energy than the best steam-engine now constructed, while it is inferior to certain gas-engines which are said to return