present forms.[202] [201] Paper by Coleman Sellers on “Oliver Evans and his Inventions.” _Journal of the Franklin Institute_, Vol. CXXII, p. 1. [202] Sections of Evans’ mills are shown in the _American Machinist_ of November 7, 1907, and December 17, 1914. In both cases the conveyor system was arranged to take material either from wagons on one side of the mill or from boats on the opposite side. Evans moved to Philadelphia some time prior to 1790. In 1800 he had a mill near Third and Market Streets and the next year was selling mill supplies at Ninth and Market Streets. As a boy he had become interested in the steam engine. A description of the Newcomen engine fell into his hands and he was struck with the fact that the steam was used only to produce a vacuum and saw that more power could be obtained if it were used to produce pressure. After his removal to Philadelphia he made an engine 6 inches diameter by 18 inches stroke, which was running in 1802, grinding plaster of Paris and sawing wood. It cost, boiler and all, more than $3700 and nearly impoverished him. Its successful operation, however, led to an order for an engine to drive a steamboat on the Mississippi, which was sent to New Orleans but never used for its original purpose. The boat it was intended for had been stranded high and dry during a flood, so the engine was set to running a saw mill and later a cotton press. In 1803 Evans began business as a regular engine builder and was unquestionably the first one in the United States. He advocated long stroke engines operating under high steam pressure, of which he had built fifty by 1816. In 1804 he built a flat bottomed boat, fitted with a steam driven, chain bucket dredge, which he called the “_Oruktor Amphibolos_” or in good English the Amphibious Digger. It was built more than a mile from the river, and was mounted on rollers connected with the engine. After moving around what is now the City Hall Square each day for several days, the boat walked out Market Street to the Schuykill and into the water; its rollers were disconnected, a stern paddle wheel substituted, and it steamed down the Schuykill and around up the Delaware to the city. In 1805 he advertised a new book, “The Young Engineer’s Guide,” which he intended to be very complete and “abstruse.” Disappointed in his application for the extension of his patents and crippled by his first engine ventures, he issued it much abridged, with only part of the illustrations planned, and called it “The Abortion of the Young Engineer’s Guide.” The proportions given in this book for one of his steam engines were: diameter of cylinder, 20 inches; stroke, 5 feet; steam pressure, 194 to 220 pounds. The boilers were of cast iron, 30 inches in diameter, 24 feet long, fired at one end, with a single return flue. An engine was actually built to these proportions for the Fairmount Water Works. It may be added that the boilers burst on three different occasions.