[Illustration] CHAPTER V. _THE MODERN STEAM-ENGINE._ "Voilà la plus merveilleuse de toutes les Machines; le Mécanisme ressemble à celui des animaux. La chaleur est le principe de son mouvement; il se fait dans ses différens tuyaux une circulation, comme celle du sang dans les veines, ayant des valvules qui s'ouvrent et se ferment à propos; elles se nourrit, s'évacue d'elle même dans les temps réglés, et tire de son travail tout ce qu'il lui faut pour subsister. Cette Machine a pris sa naissance en Angleterre, et toutes les Machines à feu qu'on a construites ailleurs que dans la Grande Brétagne ont été exécutées par des Anglais."--BELIDOR. THE SECOND PERIOD OF APPLICATION--1800-1850 (CONTINUED). THE STEAM-ENGINE APPLIED TO SHIP-PROPULSION. Among the most obviously important and most inconceivably fruitful of all the applications of steam which marked the period we are now studying, is that of the steam-engine to the propulsion of vessels. This direction of application has been that which has, from the earliest period in the history of the steam-engine, attracted the attention of the political economist and the historian, as well as the mechanician, whenever a new improvement, or the revival of an old device, has awakened a faint conception of the possibilities attendant upon the introduction of a machine capable of making so great a force available. The realization of the hopes, the prophecies, and the aspirations of earlier times, in the modern marine steam-engine, may be justly regarded as the greatest of all the triumphs of mechanical engineering. Although, as has already been stated, attempts were made at a very early period to effect this application of steam-power, they were not successful, and the steamship is a product of the present century. No such attempts were commercially successful until after the time of Newcomen and Watt, and at the commencement of the nineteenth century. It is, indeed, but a few years since the passage across the Atlantic was frequently made in sailing-vessels, and the dangers, the discomforts, and the irregularities of their trips were most serious. Now, hardly a day passes that does not see several large and powerful steamers leaving the ports of New York and Liverpool to make the same voyages, and their passages are made with such regularity and safety, that travelers can anticipate with confidence the time of their arrival at the termination of their voyage to a day, and can cross with safety and with comparative comfort even amid the storms of winter. Yet all that we to-day see of the extent and the efficiency of steam-navigation has been the work of the present century, and it may well excite our wonder and our admiration.