What Watt did next

Despite his financial success, Watt was not a natural businessman and he wrote in a letter:

I would rather face a loaded cannon than settle an account or make a bargain. In short I find myself out of my sphere when I have anything to do with mankind; it is enough for an engineer to force Nature, and to bear the vexation of her getting the better of him.

These business difficulties inspired one of his lesser-known inventions. With his commercial partner, Watt had built a thriving company that supplied steam-driven pumps to mines. However, with the company’s success, the volume of paperwork he was faced with increased and Watt struggled to find suitable clerks to copy documents. With Joseph Black (see above), Watt invented a novel system to copy documents. The pair developed a gelatinous ink which was used to write the first version of a document. The document was dampened and pressed against another thin sheet by passing the two documents between two rollers. The copy was only legible if read through the back of the copied sheet to overcome the mirroring produced by the copying process. Watt patented the device and, in the first year after in went on sale, sold 200 of the copiers, including a number to Thomas Jefferson. Later in his career, Watt worked on a device for copying sculptures using a system of parallel, hinged arms. He never completed the design but, 20 years after Watt’s attempt, the sculptor Benjamin Cheverton patented a working device based on Watt’s idea.