When the primeval man first turned upon himself the critical light of introspection, and observed his own deficiencies, there were born within him both the desire and the determination to supplement his weakness, and become the ruling factor in the world’s destiny. The strength of his arm unaided could not cope with that of the wild beast, he could not travel so fast as the animal, nor soar so high as the bird, nor traverse the waters of the sea like the fish. The magnificent power of the elements first inspired him with awe, then was worshiped as a god, and he trembled in his weakness. Then he began to invent, and seeing in physical laws an escape from his fears, and a solution for his ambitions, he trained these forces and made them subservient to his will, and established his right to rule. Out of the maze of the centuries a steam engine is born--not all at once, for that would be inconsistent with the law of evolution--but gradually growing first into practicability, then into efficiency, and finally into perfection, it stands to-day a beautiful monument of man’s ingenuity, throbbing with life and energy, and moving the world. What has not the steam engine done for the Nineteenth Century? It speeds the locomotive across the continent faster and farther than the birds can fly; no fish can equal the mighty steamship on the sea; it grinds our grain; it weaves our cloth; it prints our books; it forges our steel, and in every department of life it is the ubiquitous, tireless, potent agency of civilization. Does the ambitious young philosopher predict that electricity will supersede steam? It is not yet a rational prophecy, for the direct production of electricity from the combustion of coal is still an unsolved problem, and behind the electric generator can always be found the steam engine, modestly and quietly giving its full life’s work to the dynamo, which it actuates, and caring nothing for the credit, unmindful of the beautiful and striking manifestations of electricity which astonish the world, but humbly doing its duty with a silent faith that the law of correlation of force will always lead the way back to the steam engine, and place it where it belongs, at the head of all useful agencies of man. The Nineteenth Century did not include in its discoveries the invention of the steam engine. The great gift of James Watt was one of the legacies which it received from the past, but the economical, efficient, graceful, and mathematically perfect engine of to-day is the product of this age. [Illustration: FIG. 75.--HERO’S ENGINE, 150 B. C.]