In 1851 Elijah D. Marshall, who had established a business of engraving rolls for printing calicos in 1848 and had a small shop at Twentieth and Callowhill Streets in Philadelphia, offered Bement a partnership. He moved to Philadelphia in September of that year, and with Marshall and Gilbert A. Colby, a nephew, he began the manufacture of machine tools under the name of Marshall, Bement & Colby, thus starting only a year or so after Sellers. Marshall was a large man, dignified and deliberate in speech. Bement was strong, vigorous, a born designer, a remarkably rapid draftsman, and had a capacity for work rarely equalled. Colby was also a man of considerable mechanical ability, with advanced business ideas. Their shop consisted of a single three-storied, stone, whitewashed building, 40 by 90 feet. Their entire machine shop was on the first floor, with a 10- by 12-foot room for an office. The engine, boiler and blacksmith shop were in small outbuildings. Part of the second floor was rented to another factory and the rest was sometimes used for religious meetings, while the third floor was used for engraving printing rolls. Their tools were few and crude; among them were a 36-inch lathe with a wooden bed and iron straps for ways, and a 48-inch by 14-foot planer with ornate Doric uprights. Marshall and Colby soon retired, the latter going to Niles, Mich., where he was very successful. James Dougherty, an expert foundryman, and George C. Thomas entered the firm, which became Bement & Dougherty, the plant being known as the “Industrial Works.” Mr. Thomas contributed considerable capital, and a new shop and a foundry were built. At the same time they installed a planer 10 feet wide by 8 feet high, to plane work 45 feet long, a notable tool for that day. After a few years of struggle, the plant began to grow rapidly and at one time was the largest of its kind in the country. Bement and Sellers were among the first to concentrate wholly on tool building. They confined themselves to work of the highest quality. Both made much heavier tools, as we have said, than the New England builders, their only competitors, and in a short time had established great reputations. Bement relied little on patent protection, trusting to quality and constant improvement. Thomas retired from the partnership in 1856 and Dougherty in 1870; and Clarence S. Bement joined the firm, which became William B. Bement & Son. John M. Shrigley became a partner in 1875, William P. Bement in 1879, and Frank Bement in 1888.