["A Machine, receiving at distant times and from many hands new combinations and improvements, and becoming at last of signal benefit to mankind, may be compared to a rivulet swelled in its course by tributary streams, until it rolls along a majestic river, enriching, in its progress, provinces and kingdoms. "In retracing the current, too, from where it mingles with the ocean, the pretensions of even ample subsidiary streams are merged in our admiration of the master-flood, glorying, as it were, in its expansion. But as we continue to ascend, those waters which, nearer the sea, would have been disregarded as unimportant, begin to rival in magnitude and share our attention with the parent stream; until, at length, on our approaching the fountains of the river, it appears trickling from the rock, or oozing from among the flowers of the valley. "So, also, in developing the rise of a machine, a coarse instrument or a toy may be recognized as the germ of that production of mechanical genius, whose power and usefulness have stimulated our curiosity to mark its changes and to trace its origin. The same feelings of reverential gratitude which attached holiness to the spot whence mighty rivers sprang, also clothed with divinity, and raised altars in honor of, inventors of the saw, the plough, the potter's wheel, and the loom."--STUART.] THE GROWTH OF THE STEAM-ENGINE. CHAPTER I. _THE STEAM-ENGINE AS A SIMPLE MACHINE._ SECTION I.--THE PERIOD OF SPECULATION--FROM HERO TO WORCESTER, B. C. 200 TO A. D. 1650. One of the greatest of modern philosophers--the founder of that system of scientific philosophy which traces the processes of evolution in every department, whether physical or intellectual--has devoted a chapter of his "First Principles" of the new system to the consideration of the multiplication of the effects of the various forces, social and other, which are continually modifying this wonderful and mysterious universe of which we form a part. Herbert Spencer, himself an engineer, there traces the wide-spreading, never-ceasing influences of new inventions, of the introduction of new forms of mechanism, and of the growth of industrial organization, with a clearness and a conciseness which are so eminently characteristic of his style. His illustration of this idea by reference to the manifold effects of the introduction of steam-power and its latest embodiment, the locomotive-engine, is one of the strongest passages in his work. The power of the steam-engine, and its inconceivable importance as an agent of civilization, has always been a favorite theme with philosophers and historians as well as poets. As Religion has always been, and still is, the great _moral_ agent in civilizing the world, and as Science is the great _intellectual_ promoter of civilization, so the Steam-Engine is, in modern times, the most important _physical_ agent in that great work.