Jesse Ramsden followed duc de Chaulnes by five years in the production of his dividing engine. As with the prior inventions, Ramsden's used a tangent screw mechanism to advance the machine from one position to another. However, he had developed a screw-cutting lathe that was particularly advanced and produced a superior product.Daniel J. Boorstin, The Discoverers; A history of man's search to know his world and himself, Random House, 1983, This engine was developed with funding from the Board of Longitude on condition that it be described in detail (along with the related screw-cutting lathe) and not be protected by patent. This allowed others to freely copy the device and improve on it. In fact, the Board required that he teach others to construct their own copies and make his dividing engine available to graduate instruments made by others.
