Ericsson, John. Engineer. Born in Lanzbanshyttan, Sweden, July 31, 1803. At the age of 12 Ericsson became cadet of engineers, and at 17 entered the Swedish army. In 1827 he was promoted captain. In 1828 he constructed a flame engine, and went to London to introduce it, resigning his captaincy in the army. He also produced in succession an instrument for sea-sounding, a hydrostatic weighing machine, and a tubular steam boiler, besides other important devices. In 1833 he constructed the caloric engine, and in 1853 the ship "Ericsson," of 2,000 tons, propelled by this motor. In 1836 Ericsson invented and patented the screw propeller, and in 1839 he came to the United States where, in 1841, he designed for the government the screw-propelled war ship "Princeton." This was the pioneer screw war ship. It carried a 12-inch wrought-iron gun, designed by Ericsson, and a wrought-iron gun carriage, which absorbed the recoil without breaking. In 1861 Ericsson built for the United States government, in 100 days, the iron-clad ship "Monitor" which, on March 9, 1862, in Hampton Roads, engaged the Confederate iron-clad ram "Merrimac." In 1881 Ericsson built for the United States a vessel called the "Destroyer." His later scientific investigations included computations of the influences that retard the earth's rotary motion, and the intensity of solar heat. Ericsson died in 1889.