Petition of Jonathan Carter Hornblower

Manuscript 'Reasons for Mr. Hornblower's petitioning the Honourable House of Commons for an Act to extend the term of his patent', [24 Feb 1792]; the patent had been granted in 1781 for 14 years, permitting the use of his steam engine in the Cornish mines. The case of James Watt is cited: in 1774 he obtained an extension of a patent 'of a similar nature, for 25 years certain'.

Jonathan Carter Hornblower (1753-1815) was the British inventor of the double-beat valve, the first reciprocating compound steam engine. Hornblower's invention, patented in 1781, was a steam engine with two cylinders, a significant contribution to efficiency. The firm of James Watt (Boulton & Watt) challenged his invention, claiming infringement of patent. With the decision against him, Hornblower lost the opportunity to further develop the compound engine. Hornblower patented other inventions, a rotative engine and a steam wheel, or steam engine, and amassed a fortune in engineering. Hornblower died in 1815.

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Enclosed in a Goldsmiths' Library volume lettered 'Hornblower & Windwood-Address to Adventurers in the mines of Cornwall, 1788', including An address to the lords, adventurers and others, concern'd in the mines of Cornwall (1788; G.L. Cat. 13546).

Collection level description.

9¼" x 7¼"

Compiled by Sarah Aitchison as part of the RSLP AIM25 Project.

Further material relating to Jonathan Hornblower may be found in the Royal Cornwall Museum, Truro, and the Birmingham City Archives.

Copies may be made, subject to the condition of the original. Copying must be undertaken by the Palaeography Room staff, who will need a minimum of 24 hours to process requests.

See Journal of the House of Commons , XLVII.