Jonathan Hornblower (5 July 1753 – 23 February 1815)^[1] was an English pioneer ofsteam power.

The son ofJonathan Hornblower the Elder and the brother ofJabez Carter Hornblower, two fellow pioneers, the young Hornblower was educated atTruro Grammar School. He wasbaptised at Trelever on 25 July 1773, aged 20 (he and his family were much involved in Baptist churches in Cornwall), and wasapprenticed to a metal-working tradesman atPenryn.^[2] He married twice, first to his cousin Rosamund Phillips in 1775 and later to Elizabeth Jordan with whom he had two surviving daughters, Rosamund (1789) and Elizabeth (1790). He died on 23 February 1815 and is buried inSt Gluvias Churchyard.

He invented thecompound steam engine in 1781 and patented it on 16 July in the same year. This type of engine has two cylinders, an evolution from the single low pressure, condensing engines of Newcomen and later Watt (who introduced the separate condenser), it introduced a high-pressure cylinder before the low-pressure cylinder. The principle is that the steam first expands in the high-pressure cylinder and afterwards expands again in the low-pressure cylinder. Even though this was a revolutionary new steam technology, he was unfortunately prevented from pursuing his invention by litigation withJames Watt (Boulton & Watt) overintellectual property.^[3] His compound engine principle was not revived until 1804 (byArthur Woolf^[3]) following the expiration of Boulton and Watt's patent. Hornblower's compound engine principle contributed significantly to the increases in steamengine efficiency,^[3] and it was the foundation of the expansion engine.

See AlsoMcNaught'ed Engines

After the patent litigation with Boulton & Watt, Hornblower came up with an idea for a new kind ofrotary engine. He worked on it for several years and patented it on 5 June 1798. The engine's construction was the most complex so far, but as before he ran into trouble with Watt's patents on these subjects.

He invented thedouble-beat steam valve around 1800.^[4] This valve is a type of poppet valve, it can open against a high pressure with a minimum of force, usually operated by trip valve gear. The valve was used in railway locomotives, beam engines, grasshopper engines and paddle steamers and became widely used during the 19th century.

In 1805 Hornblower developed a steam-wheel.^{[further explanation needed]}

Encyclopædia Britannica (2007):Jonathan Carter Hornblower.

• The compound engine
• The Case Against Intellectual Monopoly by Boldrin & Levine
• [1]
• [2]

• 1753 births
• 1815 deaths
• Engineers from Cornwall
• People from Chacewater
• British steam engine engineers
• People educated at Truro Cathedral School
• Burials in Cornwall

• Webarchive template wayback links
• Use dmy dates from April 2021
• Use British English from March 2012
• Articles with hCards
• No local image but image on Wikidata
• Wikipedia articles needing clarification from May 2016