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.