He developed other ideas and applied them.

So at last was born a steam engine that would work and multiply man's energies a thousandfold.
After one or two disastrous business experiences, such as fall to the lot of many great inventors, perhaps to test their perseverance, Watt associated himself with Matthew Boulton, a man of capital and of enterprise, owner of the Soho Engineering Works, near Birmingham.

The firm of Boulton and Watt became famous, and James Watt lived till August 19, 1819--lived to see his steam engine the greatest single factor in the new industrial era that had dawned for English-speaking folk.
Boulton and Watt, however, though they were the pioneers, were by no means alone in the development of the steam engine.

Soon there were rivals in the field with new types of engines.

One of these was Richard Trevithick in England; another was Oliver Evans of Philadelphia.