A machine that derives its moving power from the force of the steam produced from boiling water, which is very great, especially when, as in the steam engine, it is confined within a limited compass: this useful machine is one of the most valuable presents that the arts of life have received from the philosopher, and is of the greatest importance in working mines; supplying cities with water; in working metals; in many mechanical arts; and in navigation. By the aid of steam, vessels are propelled with greater swiftness than those which are wholly dependent on the winds and tides; and thus trade is facilitated, and we are enabled to communicate with distant lands in a much shorter space of time than was formerly consumed. On land, railroads are constructed, on which steam carriages run with astonishing rapidity, so that a journey which by coach and horses formerly required two or more days, may now be performed in four or five hours. _Mechanical_, belonging to Mechanics. To whom are we indebted for its invention? Its invention is by most writers ascribed to the Marquis of Worcester, an Englishman, about 1663; but it does not appear that the inventor could ever interest the public in favor of this, or his other discoveries. The steam engine of Captain Savery, also an Englishman, is the first of which any definite description has been preserved. It was invented in 1698. Since that period it has been successively improved by various persons, but it is to Mr. Watt and Mr. Boulton, of England, that it is indebted for much of its present state of perfection. By whom was the Steam Engine first applied to the purposes of Navigation? By John Fitch, of Pennsylvania. From papers in the historical collections of Pennsylvania, it appears that the first successful experiments were made at Philadelphia, in 1785, three years before the attempts at Falkirk, and on the Clyde, in Scotland. The boat made several trips on the Delaware and Schuylkill rivers, but owing to repeated accidents to her machinery, and the want of funds and competent mechanics for the necessary repairs, she was abandoned. In 1807, Robert Fulton, also of Pennsylvania, made his first experimental trip on the Hudson River, with complete success. To this distinguished and ingenious American justly belongs the honor of having brought navigation by steam to a state of perfection. In 1819, the first steamship crossed the Atlantic from Savannah to Liverpool; and in 1838, a regular communication by steamship was established between Great Britain and the United States. Since that period, ocean navigation by steam-vessels has made rapid progress, and, at the present time, numbers of steamers connect our various seaports with those of other nations, and with each other. What is the Electro-Magnetic Telegraph?