Everyone knows that James Watt “invented” the steam engine. Like so many other “inventors,” such as Morse, Daguerre, and Marconi, he put together a number of ideas as he developed the finished piece of technology. In this note, I will discuss his own contribution, and show how considerations of physics lay behind his work. Let me end by telling you a physics story about a simple little object in my collection of historical physics apparatus.

1.
John Henry
Pepper
,
The Boy’s Playbook of Science
, new edition (
George Routledge and Sons
,
London
,
1875
), p.
424
. This book, first published in the mid-1870s, is one of my treasured volumes. It was a Christmas present in 1875 to Arthur Gordon Webster from his mother. Webster later became the professor of physics at the new Clark University in Worchester, MA, and was one of the founders of the American Physical Society in 1899. The book may also be found online.
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