In November of the year 1843, the screw-steamer Midas, Captain Poor, a small schooner-rigged craft, left New York for China, on probably the first voyage of such length ever undertaken by a steamer; and in the following January the Edith, Captain Lewis, a bark-rigged screw-vessel, sailed from the same port for India and China. The Massachusetts, Captain Forbes, a screw-steamship of about 800 tons, sailed for Liverpool September 15, 1845, the first voyage of an American transatlantic passenger-steamer since the Savannah's pioneer adventure a quarter of a century before. Two years later, American enterprise had placed both screw and paddle steamers on the rivers of China--principally through the exertions of Captain R. B. Forbes--and steam-navigation was fairly established throughout the world. On comparing the screw-steamer of the present time with the best examples of steamers propelled by paddle-wheels, the superiority of the former is so marked that it may cause some surprise that the revolution just described should have progressed no more rapidly. The reason of this slow progress, however, was probably that the introduction of the rapidly-revolving screw, in place of the slow-moving paddle-wheel, necessitated a complete revolution in the design of their steam-engines; and the unavoidable change from the heavy, long-stroked, low-speed engines previously in use, to the light engines, with small cylinders and high piston-speed, called for by the new system of propulsion, was one that necessarily occurred slowly, and was accompanied by its share of those engineering blunders and accidents that invariably take place during such periods of transition. Engineers had first to learn to design such engines as should be reliable under the then novel conditions of screw-propulsion, and their experience could only be gained through the occurrence of many mishaps and costly failures. The best proportions of engines and screws, for a given ship, were determined only by long experience, although great assistance was derived from the extensive series of experiments made with the French steamer Pelican. It also became necessary to train up a body of engine-drivers who should be capable of managing these new engines; for they required the exercise of a then unprecedented amount of care and skill. Finally, with the accomplishment of these two requisites to success must simultaneously occur the enlightenment of the public, professional as well as non-professional, in regard to their advantages. Thus it happens that it is only after a considerable time that the screw attained its proper place as an instrument of propulsion, and finally drove the paddle-wheel quite out of use, except in shoal water.