From these signs Boulton saw that, in the event of the engine proving successful, he and his partner would have to defend the invention against a host of pirates; and he became persuaded that he would not be justified in risking his capital in the establishment of a steam-engine manufactory unless a considerable extension of the patent-right could be secured. To ascertain whether this was practicable, Watt proceeded to London in the beginning of 1775, to confer with his patent agent and take the opinion of counsel on the subject. Mr. Wedderburn, who was advised with, recommended that the existing patent should be surrendered, and in that case he did not doubt that a new one would be granted. While in London, Watt looked out for possible orders for his engine: “I have,” he wrote Boulton, “a prospect of two orders for fire-engines here, one to water Piccadilly, and the other to serve the south end of Blackfriars Bridge with water. I have taken advice of several people whom I could trust about the patent. They all agree that an Act would be much better and cheaper, a patent being now 130_l._, the Act, if obtainable, 110_l._ The present patent has eight years still to run, bearing date January, 1769. I understand there will be an almost unlimited sale for wheel-engines to the West Indies, at the rate of 100_l._ for each horse’s power.”[140]
[140] Watt to Boulton, 31st January, 1775. Boulton MSS.
Watt also occupied some of his time in London in superintending the adjustment of weights manufactured by Boulton and Fothergill, then sold in considerable quantities through their London agent. That he continued to take an interest in his old business of mathematical instrument making is apparent from the visits which he made to several well-known shops. One of the articles which he examined with most interest was Short’s Gregorian telescope. At other times, by Boulton’s request, he went to see the few steam-engines then at work in London and the neighbourhood, and make inquiries as to their performances. With that object he examined the engines at the New River, Hungerford, and Chelsea. At the latter place, he said, “it was impossible to try the quantity of injection, and the fellow told me lies about the height of the column of water.” But Watt soon grew tired of London, “running from street to street all day about gilding,” inquiring after metal-rollers, silver-platers, and button-makers. He did his best, however, to execute the commissions which Boulton from time to time sent him; and when these were executed, he returned to Birmingham to confer with his friends as to the steps to be taken with respect to the patent. The result of his conferences with Boulton and Small was, that it was determined to take steps to apply for an Act for its extension in the ensuing session of Parliament.