Watt revisited Cornwall in 1781 to make an inspection of all the engines. Much he found needing attention and improvement. His evenings were spent designing "road steam-carriages." This was before the day of railroads, and the carriages were to be driven by steam over the ordinary coach roads. He filled a quarto drawing-book with different plans for these, and covered the idea in one of his patent specifications. Boulton suggested in 1781 that the idea of rotary motion should be developed, which Watt had from the first regarded as of prime importance. It was for this he had invented his original wheel engine, and in his first patent of 1769 he describes one method of securing it. It occurred to him that the ordinary engine might be adapted to give the rotary motion. He wrote from Cornwall to Boulton: "As to the circular motion, I will apply it as soon as I can." He prepared a model upon his return to Soho, using a crank connected with the working-beam of the engine for that purpose, which worked satisfactorily. There was nothing new in the crank motion; it was used on every spinning-wheel, grind-stone and foot-lathe turned by hand, but its application to the steam-engine was new. As early as 1771, he writes: I have at times had my thoughts a good deal upon the subject. In general, it appears to me that a crank of a sufficient sweep will be by much the sweetest motion, and perhaps not the dearest, if its durability be considered ... I then resolved to adopt the crank ... Of this I caused a model to be made, which performed to satisfaction. But being then very much engaged with other business, I neglected to take a patent immediately, and having employed a blackguard of the name of Cartwright (who was afterward hanged), about this model, he, when in company with some of the same sort who worked at Wasborough's mill, and were complaining of its irregularities and frequent disasters, told them he could put them in a way to make a rotative motion which would not go out of order nor stun them with its noise, and accordingly explained to them what he had seen me do. Soon after which, John Steed, who was engineer at Wasborough's mill, took a patent for a rotative motion with a crank, and applied it to their engine. Suspicions arising of Cartwright's treachery, he was strictly questioned, and confessed his part in the transaction when too late to be of service to us. Overtures were made by Wasborough to exchange patents and work together, which Watt scornfully rejected. He writes: Though I am not so saucy as many of my countrymen, I have enough innate pride to prevent me from doing a mean action because a servile prudence may dictate it ... I will never meanly sue a thief to give me my own again unless I have nothing left behind. His blood was up. No dealings with rascals!