“Repair this model, if you please.” These words were spoken to James Watt, an instrument maker at the University of Glasgow, Scotland, in 1764. The model showed how a steam engine worked, but what a steam engine! The original engine of which this miniature working model was a copy, was heavy and clumsy. Worse than that, it was extremely wasteful of the steam that ran it and therefore of the coal that was burned to generate the steam. Such steam engines, built by an English blacksmith named Newcomen, had been used for 40 years, but only in mines to pump out water. Wasteful or not, one steam pump, night and day, did the work of 50 men. Watt had an orderly mind. Moreover, he was a Scotsman, with a Scotsman’s traditional dislike of waste. Any machine that wasted most of the fuel that made it go was something to be improved, not merely repaired. Watt worked on the model and found out what the matter was. The steam was turned back into water (condensed) in the same part of the engine where it pushed against the piston, that is, in the cylinder. Only hot cylinders worked well, yet condensing steam in the cylinder cooled it off. Then why not condense the steam somewhere else? That is what Watt did. He worked for years planning a new model with a separate cooling chamber for the steam. Now, with the same amount of fuel, the engine did two or three times as much work as before and why not let steam, like flowing water, turn Wheels? Watt hitched up the steam engine in such a way that it could turn wheels and run machinery. He also built a governor to keep engines going at the same rate of speed. These inventions, in turn, …
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