Thus we are to-day witnessing the literal fulfillment of the predictions of Oliver Evans and of John Stevens, and almost that contained in the couplets written by the poet Darwin, who, more than a century ago, before even the earliest of Watt's improvements had become generally known, sang: "Soon shall thy arm, unconquered Steam, afar Drag the slow barge, or drive the rapid car; Or, on wide-waving wings expanded, bear The flying chariot through the fields of air." [Illustration] CHAPTER VII. _THE PHILOSOPHY OF THE STEAM-ENGINE._ THE HISTORY OF ITS GROWTH; ENERGETICS AND THERMO-DYNAMICS. "Of all the features which characterize this progressive economical movement of civilized nations, that which first excites attention, through its intimate connection with the phenomena of production, is the perpetual and, so far as human foresight can extend, the unlimited growth of man's power over Nature. Our knowledge of the properties and laws of physical objects shows no sign of approaching its ultimate boundaries; it is advancing more rapidly, and in a greater number of directions at once, than in any previous age or generation, and affording such frequent glimpses of unexplored fields beyond as to justify the belief that our acquaintance with Nature is still almost in its infancy."--MILL. The growth of the philosophy of the steam-engine presents as interesting a study as that of the successive changes which have occurred in its mechanism.