Simple tests to determine whether soil needs nitrogen, phosphates, or potash devised by George Hoffer, _German_ ... pasteurization introduced by Julius Moldenhawar, _Dane_ ... orange that will stay on tree for months after ripening propagated by Lue Gim Gong, _Chinese_ ... honey industry revolutionized by Frank Jaeger, _Yugoslav_. Early cooperative creamery at Clark’s Grove, Minn., organized under leadership of Hans Jensen, _Dane_ ... first to find trichina spiralis in hogs and hookworm in cats was Joseph Leidy, _German_ ... International Institute of Agriculture established by David Lubin, _Polish-Jew_. Our Gifts to Industry and Commerce _Inventions_ First clock in America constructed to strike the hours built by Benjamin Banneker, _Negro_, in 1790 ... early flour-milling machinery by Oliver Evans, _Welsh_ ... iron comb, made by a _Negro_ to help cotton pickers, gave Eli Whitney, _English_, idea for his cotton gin ... screw propeller and revolving turret on battleship invented by John Ericsson, _Swede_ ... first patent to a _Negro_ granted to Henry Blair for corn harvester in 1834 ... comb-making machine built by Nathaniel Jones, _Welsh_. First zipper fastener invented by Gideon Sundbäck, _Swede_ ... green coloring matter used in our paper dollar invented by Dr. Seropian, _Armenian_ ... machine for lasting shoes built by Jan Matzeliger, _Haitian_, in 1852 ... self-starter automobile clutch invented by Victor Bendix, _Swede_; also developed four-wheel brakes and carburetor ... steam-boiler furnace, electrical air-brakes, and incubator invented by Granville T. Woods, _Negro_ ... inventor of carborundum was E. G. Acheson, _English_. [Illustration] Sewing machine invented by Elias Howe, _English_, in 1846 ... lubricating cup, used on locomotives and marine engines, invented by Elijah J. McCoy, _Negro_ ... discovery of artificial rubber by Father Nieuland of Notre Dame, _Belgian_, broke the British hold on rubber ... induction motors invented by Nicolas Tesla, _Yugoslav_ ... co-discoverer of process for making luminous paints was John Sochocky, _Ukrainian_ ... fireproof stairs and library bookstacks invented by Neils Poulson, _Dane_ ... Stilson wrench invented by Daniel Stilson, _Swede_, in 1875.