John Ericsson, a Swedish engineer and physicist, born in the province of Wermeland in 1803. In 1814 he was appointed a cadet in the engineers, and in 1816 was employed as a leveller on the grand ship canal between the Baltic and the North sea. In 1820 he entered the Swedish army as an ensign, was soon promoted to a lieutenancy, and was employed in surveys in northern Sweden, attaining the rank of captain. In 1826 he visited England, with the view of introducing his invention of a flame engine; but with mineral fuel it proved a failure. Soon afterward he resigned his commission and devoted himself to mechanical pursuits. Numerous inventions followed, among others the steam boiler on the principle of artificial draft, which was extensively adopted in London for manufacturing purposes, effecting a great saving of fuel, and dispensing with the huge smoke stacks; and it was adapted to railway locomotion on the Liverpool and Manchester railway in the fall of 1829. The directors had offered a prize for the best locomotive engine, and the lightest and fastest engine exhibited on this occasion was the Novelty, which, guided by its inventor Ericsson, started off at the rate of 50 miles an hour.

The principle of artificial draft is still retained in all locomotive engines; but a different mode of producing it was accidentally discovered so soon after the display of the Novelty, that the original inventor derived no advantage from it. The lightness and compactness of this boiler led to many new applications of steam, and among others to Ericsson's construction of a steam fire engine, which was entirely successful. He constructed a similar engine of greater power for the king of Prussia. For this invention he received the prize medal of the mechanics' institute of New York. In 1833 he reduced to practice his long cherished project of a caloric engine, and submitted the result to the scientific world in London. The invention excited very general interest, lectures were delivered in explanation and illustration of its principle by Dr. Lardner and by Professor Faraday, and it was highly approved by Dr. Andrew Ure and Sir James Phillips. In 1836 he successfully applied the propeller to purposes of navigation; but failing to impress the British admiralty with the value of his invention, in 1839 he came to New York. In 1841 he was employed in the construction of the ship of war Princeton, which was the first steamship ever built with the propelling machinery under the water line and out of the reach of shot.

The Princeton was distinguished for numerous mechanical novelties besides the propeller; among which were a direct-acting steam engine of great simplicity, the sliding telescope chimney, and gun carriages with machinery for checking the recoil of the gun. In the United States division of the London industrial exhibition in 1851, Ericsson exhibited the distance instrument, for measuring distances at sea; the hydrostatic gauge for measuring the volume of fluids under pressure; the reciprocating fluid meter for measuring the quantity of water which passes through pipes during definite periods; the alarm barometer; the pyrometer, intended as a standard measure of temperature from the freezing point of water up to the melting point of iron; a rotary fluid meter, the principle of which is the measurement of fluids by the velocity with which they pass through apertures of definite dimensions; and a sea lead, contrived for taking soundings at sea without rounding the vessel to the wind and independently of the length of the lead line. For these he received the prize medal of the exhibition.

In 1852 he brought out a new form of caloric engine in the ship Ericsson. It propelled this ship of 2,000 tons from New York to Alexandria on the Potomac, in very rough weather, in the latter part of February, 1853. On this trip the engines were in operation for 73 hours without being stopped for a moment, and without requiring the slightest adjustment, the consumption of fuel being only five tons in 24 hours; but her speed was not great enough, and the caloric engines were subsequently replaced by steam engines. For several years Ericsson devoted himself to the improvement and perfection of the caloric engine and its application to pumping, printing, hoisting, grinding, sawing, turning light machinery of various kinds, working telegraphic instruments and sewing machines, and propelling boats. (See Caloric Engine.) At the commencement of the civil war he entered into contract with the government for the construction of iron war vessels with revolving turrets for the guns, the first practical application of the principle.

The first one, the Monitor, was completed in 100 days, reached Hampton Roads on the evening of March 8, 1862, and on the following day defeated and blockaded the confederate iron-clad Merrimack. Considerable improvements were made by him in the vessels (called monitors from the name of the first one) subsequently built. He has since devoted much attention to the construction of solar engines. - His brother Nils, born Jan. 31, 1802, served in the Swedish army, and from 1858 to 1863 in the navy. He was director of Swedish railways, constructed the canal between the Saiman and the gulf of Finland, the docks of Stockholm, and other public works, and was ennobled. He died in Stockholm Sept. 8, 1870.