The uses of Watt's steam-engine began to be recognised as available for manufacturing purposes. It was then found necessary to invent some method by which continuous rotary motion should be secured, so as to turn round the moving machinery of mills. With this object Watt had invented his original wheel-engine. But no steps were taken to introduce it into practical use. At length he prepared a model, in which he made use of a crank connected with the working beam of the engine, so as to produce the necessary rotary motion. There was no originality in this application. The crank was one of the most common of mechanical appliances. It was in daily use in every spinning wheel, and in every turner's and knife-grinder's foot-lathe. Watt did not take out a patent for the crank, not believing it to be patentable. But another person did so, thereby anticipating Watt in the application of the crank for producing rotary motion. He had therefore to employ some other method, and in the new contrivance he had the valuable help of William Murdock. Watt devised five different methods of securing rotary motion without using the crank, but eventually he adopted the "Sun-and-planet motion," the invention of Murdock. This had the singular property of going twice round for every stroke of the engine, and might be made to go round much oftener without additional machinery. The invention was patented in February, 1782, five Years after Murdock had entered the service of Boulton and Watt. Murdock continued for many years busily occupied in superintending the Cornish steam-engines. We find him described by his employers as "flying from mine to mine," putting the engines to rights. If anything went wrong, he was immediately sent for. He was active, quick-sighted, shrewd, sober, and thoroughly trustworthy. Down to the year 1780, his wages were only a pound a week; but Boulton made him a present of ten guineas, to which the owners of the United Mines added another ten, in acknowledgment of the admirable manner in which he bad erected their new engine, the chairman of the company declaring that he was "the most obliging and industrious workman he had ever known." That he secured the admiration of the Cornish engineers may be obvious from the fact of Mr. Boaze having invited him to join in an engineering partnership; but Murdock remained loyal to the Birmingham firm, and in due time he had his reward.