Editing James Watt (section)

===Copying machine===
[[File:Portable Copying Machine by James Watt & Co.jpg|thumb|Portable Copying Machine by James Watt & Co. Circa 1795]]
Before 1780, there was no good method for making copies of letters or drawings. The only method sometimes used was a mechanical one using multiple linked pens. Watt at first experimented with improving this method, but soon gave up on this approach because it was so cumbersome. He instead decided to try to physically transfer ink from the front of the original to the back of another sheet, moistened with a solvent, and pressed to the original. The second sheet had to be thin, so that the ink could be seen through it when the copy was held up to the light, thus reproducing the original exactly.<ref>Hills, Vol. 2, pp. 190–211.</ref><ref>W. B. Proudfoot, ''Origin of Stencil Duplicating'', p. 21, as quoted at Quaritch.com, 12 October 13.</ref>

Watt started to develop the process in 1779, and made many experiments to formulate the ink, select the thin paper, to devise a method for wetting the special thin paper, and to make a press suitable for applying the correct pressure to effect the transfer. All of these required much experimentation, but he soon had enough success to patent the process a year later. Watt formed another partnership with Boulton (who provided financing) and [[James Keir]] (to manage the business) in a firm called James Watt and Co. The perfection of the invention required much more development work before it could be routinely used by others, but this was carried out over the next few years. Boulton and Watt gave up their shares to their sons in 1794.<ref>Hills, vol. 3, p. 116.</ref> It became a commercial success and was widely used in offices even into the 20th century.