not be so low—in flying-machines. There are forces, they will say, such as steam, electricity, explosions, etc., which are far more powerful than muscular contraction. Especially is electricity looked to in a vague way to do for us many wonderful things, this of flying among the number. Now, this is again a great mistake. Nerve-energy acting through muscular contraction, and supplied by the combustion of foods, such as oils, fats, starch, sugar and fibrin, together form the most perfect and efficient engine that we know anything of; i, e., will do more work with the same weight of machinery and fuel.
There was much loose talk a few years ago about condensing and storing electricity in immense quantity, in small space, by the use of Faure's battery. Millions of foot-pounds, it was said, may be thus condensed and stored in a small box and carried about. To the unreflecting, millions of foot-pounds seems a very large quantity. Extravagant expectations were thus raised in the popular mind. I remember at that time talking with a very intelligent gentleman on this very subject of flying-machines; and he, in rebuttal of my argument, suggested the use of stored electricity. "Why," said I, "there is more energy stored in a piece of coal that may be put in the vest-pocket than can be stored in a Faure's battery weighing three hundred pounds!" Faure's battery is doubtless a good thing, but chiefly, like a fly-wheel, not for increasing the amount but regulating the flow of force. He then suggested the enormous force of explosives, such as the nitro-compounds. The feeding of these to the engine might, he rightly thought, be so regulated as to supply a continuous force. But here also lurks a fallacy, the result again of a misconception. The force of such compounds is characterized by great intensity rather than great quantity. The whole force is compressed into an almost infinitely small space of time, and therefore very intense. But stretch it out as a continuous force and it becomes no greater, probably less, than that of an equal weight of burning coal. There is probably no greater available energy in the world than that produced by the burning of carbon and hydrogen. It is this form of energy that we use in steam-engines; this we find most powerful and economical in making electricity; this, also, is what is used in the animal machine. The only question that remains, then, is the relative economy of its use. Now, I think it will be admitted on all hands that no known engine compares in this respect with the animal body. It is acknowledged by mechanical engineers that the animal machine, burning hydrocarbonaceous food, and acting through nerve and muscle, more nearly approaches the theoretical limit of possible work than any, even the best, steam-engines. More accurately, the animal body is about twice as effective as the best Cornish engine.