The introduction of the changes just noted finally led to the last great change in the form of the marine steam-engine, and a revolution was inaugurated, which, however, only became complete in the succeeding period. The non-success of Hornblower and of Wolff, and others who had attempted to introduce the "compound" or double-cylinder engine on land, had not convinced all engineers that it might not yet be made a successful rival of the then standard type; and the three or four steamers which were built for the Hudson River at the end of the first quarter of the nineteenth century are said to have been very successful vessels. Carrying 75 to 100 pounds of steam in their boilers, the Swiftsure and her contemporaries were by that circumstance well fitted to make that form of engine economically a success. This form of engine was built occasionally during the succeeding quarter of a century, but only became a recognized standard type after the close of the epoch to the history of which this chapter is devoted. That latest and greatest advance in the direction of increased efficiency in the marine steam-engine was, however, commenced very soon after Watt's death, and its completion was the work of nearly a half-century. [Illustration] CHAPTER VI. _THE STEAM-ENGINE OF TO-DAY._ ... "And, last of all, with inimitable power, and 'with whirlwind sound,' comes the potent agency of steam. In comparison with the past, what centuries of improvement has this single agent comprised in the short compass of fifty years! Everywhere practicable, everywhere efficient, it has an arm a thousand times stronger than that of Hercules, and to which human ingenuity is capable of fitting a thousand times as many hands as belonged to Briareus. Steam is found in triumphant operation on the seas; and, under the influence of its strong propulsion, the gallant ship-- 'Against the wind, against the tide, Still steadies with an upright keel.' It is on the rivers, and the boatman may repose on his oars; it is on highways, and exerts itself along the courses of land-conveyance; it is at the bottom of mines, a thousand feet below the earth's surface; it is in the mills, and in the workshops of the trades. It rows, it pumps, it excavates, it carries, it draws, it lifts, it hammers, it spins, it weaves, it prints. It seems to say to men, at least to the class of artisans: 'Leave off your manual labor; give over your bodily toil; bestow but your skill and reason to the directing of my power, and I will bear the toil, with no muscle to grow weary, no nerve to relax, no breast to feel faintness!' What further improvement may still be made in the use of this astonishing power it is impossible to know, and it were vain to conjecture. What we do know is, that it has most essentially altered the face of affairs, and that no visible limit yet appears beyond which its progress is seen to be impossible."--DANIEL WEBSTER.