| Description | When Boulton & Watt first learnt of Jonathan Hornblower’s patent and his first engine at Radstock Colliery in 1781, they took no legal action against him for infringing James Watt’s patent. However James Watt’s advertisement in the Bristol papers of the unique features of his engine made it clear that Boulton & Watt considered Hornblower’s engine an infringement. Following the Radstock engine, Hornblower appears to have received only one order, for a very short-lived engine at Timsbury near Bath. However in 1791 he erected a successful engine at Tincroft Mine which lead to orders for around ten engines from the Cornish mining industry, one of Boulton & Watt’s major markets. When he sought to extend his patent by an Act of Parliament in 1792, Boulton & Watt vigorously and successfully opposed him. This led to increase of support for Hornblower and his partner John Winwood in the Cornish mining industry.
Boulton & Watt considered that the mines using Hornblower’s engines owed them premium payments, because they were effectively using James Watt’s invention. They were prepared to take the mine owners to court if necessary to extract payments, and gathered material in support of their case. However the question mark placed over the validity of Watt’s patent by the uncertain verdicts in the action against Edward Bull in 1793 and 1795 encouraged many mines to withhold payments, and the prosecution of these mines continued through the late 1790s.
This bundle contains correspondence about Hornblower’s early engines and expressions by Boulton & Watt that they would take action against mines using Hornblower’s engines. It also includes supporting material including legal opinions on the patents, copies of Watt’s patent and Hornblower’s bill, and the printed statements producing during Boulton & Watt’s opposition to Hornblower’s bill in 1792. The mines and engines mentioned include Radstock Colliery, Penryn Tincroft Mine, Seal Hole and Wherry Mine. "Horner" as used in the title of this bundle was one of the names Boulton & Watt frequently used to refer to the Hornblowers.
For papers relating to Boulton & Watt’s opposition to Hornblower’s bill of 1792, see 2/33—37. For drawings of Jonathan Hornblower’s engines including the Radstock and Tincroft engines see "Drawings of Engine Designs by James Watt, Bull and Hornblower’s Engines, Dutch Windmill etc.", Portfolio MS 3147/5/1339b. |