| Description | Jabez Carter Hornblower was the eldest son of the veteran Cornish engineer Jonathan Hornblower. Jabez worked for Boulton & Watt in the late 1770s, but following his work on the engine at Penryndee in Wales in 1779, Boulton & Watt dismissed him. Little is known about his subsequent career, but he may have assisted his brother Jonathan with his engines.
Around 1790 Jabez moved to London and established himself as an engine maker. He later entered a partnership with one Stephen Maberly. Maberly had acquired the patent for a "pendulum steam engine" granted to Isaac Manwaring, a saw-maker from Clerkenwell, in 1791. Hornblower made various modifications to Manwaring’s design, and he and Maberly began to sell engines from their premises in Allen Street. They were joined in the business by Maberly’s son John. The engine, which featured a separate condenser, closed cylinder tops and steam acting on the upper surface of the piston, infringed James Watt’s patent.
Boulton & Watt became aware of Hornblower and Maberly’s piracy around September 1795, when they received reports of an engine erected near Durham for William Peareth, a colliery owner. In January 1796 they issued injunctions against Hornblower, Maberly and Peareth, and throughout much of the rest of 1796 they corresponded with other concerns who had bought Hornblower and Maberly engines, seeking premium payments.
In August 1796 Stephen and John Maberly sought to come to terms with Boulton & Watt. One of their suggestions was that they become licensed manufacturers of Watt engines, which Boulton & Watt refused. They also refused to enter into a similar scheme with Edward Bull. The negotiations came to nothing, and later in the year they began an action in the Court of Common Pleas against Hornblower and Maberly.
This bundle mainly contains correspondence and memoranda from Boulton & Watt’s agents and engineers, such as Thomas Barnes and John Southern, about Hornblower and Maberly’s engines. It also includes correspondence with the users of Hornblower and Maberly’s engines, and papers relating to the proposed settlement. These documents pre-date the action in Common Pleas.
For drawings of Hornblower and Maberly’s engines, see "Designs by William Murdock, Atmospheric and Other Engines, Drawings for Court Cases," Portfolios MS 3147/5/1353b and MS 3147/5/1354c. The former portfolio includes drawings of the engine for William Peareth. |