The Life and Legend of James Watt, by David Philip Miller, tells the story of how the steam engine was invented

David Philip Miller supplies well-informed, well-written corrections to that answer. He identifies Thomas Newcomen as the actual inventor of the steam engine, while crediting Watt with "a step change in efficiency" in its use. Miller characterises Watt as "an 'improver', in a Scottish tradition". As an author, Miller (formerly a Professor at UNSW) is a most capable, readable explainer.

Miller begins his explanations by focusing on Watt's two critical improvements to steam engines. He enhanced efficiency by constructing more efficient condensers. His engines also produced rotative as well as reciprocating motion. That is, they could drive machinery, hence consolidating one of the foundations for England's Industrial Revolution. A linear connection runs between Watt's experiments and China's rise.

Miller's interest in Watt is omnivorous. Miller outlines his premises and intentions in an admirable introduction, a model of its kind, then proceeds to take the reader down one engaging, intriguing by-path after another. Chronology is succeeded by thematic approaches, each informed by deep, serious inquiry.

Miller is fascinated by how avidly Watt pursued both fortune and fame. He tries valiantly to expound Watt's apparently coherent "chemistry of heat" as well as his debt to natural philosophy. Team Watt, the contribution of the engineer's partner, workers and family to his inventions, is skilfully outlined. Miller wrestles with the affairs of the "thinking engineer" from his first "salt-laden breath" (in 1736) through his scrutiny of the condensation of steam out of a tea kettle, on to his celebrated attic workshop and his move to Birmingham, then finally to his posthumous reputation. Watt's earnings and the divergences in portraits of the inventor are rigorously appraised in their turn. Watt's long-time partner, Matthew Boulton, is also given his due, despite a flick for "habitual recklessness in financial affairs".

All this diverse material is handled so confidently and adroitly that Miller's work might also serve as an essay on the value of originality or where ideas really come from. Watt once claimed (as late as 1790) to have "tacked and sewn together the seraffo and remnants of many a man's ideas. Miller is especially thorough in tracing collaborations, borrowings and cross-fertilisations. Fittingly, both subject and author display ingenuity.