Hornblower's engine. Historical artwork of Hornblower's steam engine that was patented in 1781. Jonathan Hornblower (1753-1815) was an English engine maker. He invented this engine called the double-beat valve, which was the first reciprocating compound steam engine. It has two cylinders (left) and therefore is more efficient than engines with only one cylinder. The design was challenged by the engine makers Boulton and Watt who said it infringed their patent. Hornblower was unable to further develop this engine. Published in History and progress of the steam engine, England, 1830.