[2][3] The engines name comes from its use in Matthew Boulton's Soho Manufactory, where it was used to drive a line of 43 polishing or lapping machines, used for the production of buttons and buckles.

He developed a number of separate innovations, each of which improved the existing engines of the day, beginning with Newcomen's.

The sun and planet gear was invented by another Scottish engineer, William Murdoch, an employee of Boulton and Watt.

The planet is attached rigidly to the end of the connecting rod, hung from the beam.

The sun, and the output crankshaft, thus rotates twice for every piston cycle of the engine, twice as fast as with a conventional crank.