Editing James Watt (section)

===Patent trials===
[[File:20070616 Dampfmaschine.jpg|thumb|A steam engine built to James Watt's patent in 1848 at [[Freiberg, Saxony|Freiberg]] in Germany]]
[[Edward Bull]] started constructing engines for Boulton and Watt in Cornwall in 1781. By 1792, he had started making engines of his own design, but which contained a separate condenser, and so infringed Watt's patents. Two brothers, [[Jabez Carter Hornblower]] and [[Jonathan Hornblower]] Jnr also started to build engines about the same time. Others began to modify Newcomen engines by adding a condenser, and the mine owners in Cornwall became convinced that Watt's patent could not be enforced. They started to withhold payments to Boulton and Watt, which by 1795 had fallen on hard times. Of the total £21,000 (equivalent to £{{formatnum:{{Inflation|UK|21000|1795|{{Inflation-year|UK}}|r=-4}}}} as of {{Inflation-year|UK}}) owed, only £2,500 had been received. Watt was forced to go to court to enforce his claims.<ref>Hills, vol. 3, ch. 5 and 6.</ref>

He first sued Bull in 1793. The jury found for Watt, but the question of whether or not the original specification of the patent was valid was left to another trial. In the meantime, injunctions were issued against the [[Patent infringement|infringers]], forcing their payments of the [[Royalty payment|royalties]] to be placed in [[escrow]]. The trial on determining the validity of the specifications which was held in the following year was inconclusive, but the injunctions remained in force and the infringers, except for Jonathan Hornblower, all began to settle their cases. Hornblower was soon brought to trial in 1799, and the verdict of the four was decisively in favour of Watt. Their friend John Wilkinson, who had solved the problem of boring an accurate cylinder, was a particularly grievous case. He had erected about 20 engines without Boulton's and Watts' knowledge. They finally agreed to settle the infringement in 1796.<ref>Roll, p. 158.</ref> Boulton and Watt never collected all that was owed them, but the disputes were all settled directly between the parties or through [[arbitration]]. These trials were extremely costly in both money and time, but ultimately were successful for the firm.