In the same letter, Boulton communicated to Watt the rumours that had reached him from Scotland of more inventions of engines that were to beat Watt’s out of the field. “The cry is still, they come!” said he. “Hatley from Scotland is going with Lord Dunmore to Virginny; says that he and somebody else in Scotland have invented an engine that is three times better than yours.” Boulton recommended that a search should be made at the Patent-Office, to ascertain what was going on in new engine patents. Watt entirely approved of this, and urged that the search should be made at once. “I do not think we are safe a day to an end,” he wrote, “in this enterprising age. One’s thoughts seem to be stolen before one speaks them. It looks as if Nature had taken an aversion to monopolies, and put the same thing into several people’s heads at once to prevent them; and I begin to fear that she has given over inspiring me, as it is with the utmost difficulty that I can hatch anything new.” Notwithstanding this confession on the part of Watt, his inventive faculties were really never at any period of his life more vigorous than now; for he was rapidly maturing his rotative engine, with its various ingenious methods for securing circular motion; and working out the details of the double-cylinder expansion engine, with its many admirable contrivances hereafter to be described. Boulton continued to receive applications at Soho, from various quarters, for engines capable of working flour-mills and other machinery, and Watt himself was urged by like inquiries from manufacturers in Cornwall. “Mr. Edwards,” he wrote Boulton, “waits impatiently the success of our rotative machine. He wants a power able to lift a hammer of 700 lbs., 2 feet high, 120 times per minute.... In relation to the circular engine, an experiment should be made on a large scale, and to work a hammer. I want your ideas on that head.”[218] A fortnight later, Watt had matured his own ideas, and made the necessary declaration of his invention before a magistrate, preliminary to making the usual application for a patent.[219] [218] Watt to Boulton, 5th July, 1781. [219] “Yesterday I went to Penryn and swore that I had invented ‘certain new methods of applying the vibrating or reciprocating motion of steam or fire engines to produce a continued rotation or circular motion round an axis or centre, and thereby to give motion to the wheels of mills or other machines,’ which affidavit and petition I transmit to Mr. Hadley by this post with directions to get it passed with all due expedition.”--Watt to Boulton, 26th July, 1781.