In this decade we find the conversion of electricity into mechanical motion and many other important electrical developments, which, however, are omitted from this list as we are confining ourselves to mechanical inventions. There were marked developments in steam railroads. Stephenson built the “Rocket” which won prizes on the Liverpool and Manchester Railway, and the first locomotive was imported into this country in 1829. The tubular locomotive boiler was invented by Seguin in 1828 and Ericsson’s portable steam fire engine was built in 1830. In the previous year an important improvement in spinning mules was made when John Thorpe invented the ring frame. 1831-1840 Important railroad developments mark the opening of this decade. The famous locomotive “John Bull” was imported from England in 1831 to operate on the Camden and Amboy Railroad. The following year saw the first American-built locomotive, “Old Ironsides,” which was built at Philadelphia by the Baldwin Locomotive Works. Stephenson’s link motion, also claimed by W. T. James, was invented in 1832. However, the most important development of the decade was the invention of the reaper. Hussey’s patent was obtained in 1833 and McCormick’s the following year. Colt’s revolver (1836); Perkin’s portable ice machine (1834); Anthony’s (1831), Tolle’s (1834), and Burden’s (1835) developments in machines for making horseshoes; and Isaac Babbit’s antifriction-bearing metal are other notable developments. 1841-1850 It was in 1841 that F. E. Sickels invented the drop cut-off valve gear, and the Corliss valve gear was patented in 1849 and 1851. Nasmyth’s steam hammer was invented in 1842. Hoe’s revolving printing press was invented in 1845. The next year Sloan patented the gimlet-pointed screw. In 1847 Savage invented the time lock, and in 1849 Hibbert patented the latch needle for knitting machines. American machine-made watches appeared in 1850. However, the most important invention of the decade was Howe’s sewing machine in 1845. 1851-1860 The year 1851 saw an important improvement in the harvester when Seymour invented his self-raker, also an advance in firearms when Maynard invented the breech-loading rifle. Three years later Smith & Wesson came forth with their magazine rifle which was the forerunner of the “Winchester.” In that year Wilson invented the four-motion feed for sewing machines. One of the most notable inventions of the decade was Bessemer’s converter for producing steel (1855), and the following year Siemens produced the regenerative furnace. Gifford’s injector (1858) marked a most important advance in steam engineering. The hand-turned turret for lathes was invented by Stephen Fitch about 1853, and the automatically revolving turret was brought out in 1855.