Engraving. Jonathan Hornblower (1753-1815) patented an early form of compound steam engine. In his youth Hornblower was employed by Boulton and Watt to work on one of their engines. Hornblower worked on improving Watt's design and in 1781 had designed a single-acting compound engine with two cylinders. This design however was seen to infringe Watt's preexisting patent of the separate condenser therefore halting manufacture. Hornblower also patented designs for a rotary steam engine that again was never manufactured.
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