Boulton & Watt started legal proceedings against Bull stating that his engine was an act of piracy. The courts found in favour of Boulton & Watt in an interim judgement and injunctions were served on both Bull and Trevithick in 1795 to disallow erection of further engines of the type. The case against Bull, and the arguments put forward in his defence regarding the invalidity of Watt's patent were typical of intensifying actions, primarily against Hornblower, Trevithick and other Cornish engineers, taken by Watt during the lifetime of the patent's extension to 1800. Final judgement in Boulton & Watt's favour was made in 1799 allowing the collection of outstanding dues, this virtually coincident with Bull's death at the early age of 40.

 

In 1811, with some 17 engines of the inverted type operating in Cornwall, Trevithick applied his high pressure steam boiler to the condensing Bull pumping engine at Wheal Prosper, Gwithian, thus initiating the application of the Cornish cycle transforming the performance of the steam engine, alongside the compact atmospheric discharge winding engine and the subsequent applications on road and rail.

 

In the 1830s the Bull engine type re-emerges, in association with Messrs Harvey of Hayle, with use of high pressure steam to 40psi and expansive working to the Cornish cycle as accepted practice with the pumping engine. Exports of 60-inch engines to Mexico at the Fresnilo mine in 1835 at £1172, and 1838 at £1396 probably relate to the virtues of compact size and simplified housing. Subsequent exports include those to Spain and to South Australia from 1849.

 

With Cornish cycle engines established in use with the London water works from the 1840s, the Harvey Bull engine variant came into use with two 66-inch engines erected at Hampton for the Southwark & Vauxhall Company in 1852, followed by two 70-inch engines for the Grand Junction Company an Campden Hill in 1857 and the similar Kew Bridge engine in 1859. Others followed in London and in 1878 the two 50-inch engines supplied for Sudbrook on the Severn tunnel were to our knowledge the last manufactured. One of these was operable to 1954 and then removed for storage with the expectation that it might be displayed at some time in the future at the now closed Cardiff Industrial Museum.