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"Joule's experiment on the mechanical equivalent of heat, in which he caused paddlewheels to rotate in a vessel of water by means of falling weights W." -Hawkins, 1917

Joule's Experiment

"Joule's experiment on the mechanical equivalent of heat, in which he caused paddlewheels to rotate…

"A labratory liquid air machine used by Thomson and Joule used to cool hydrogen from a gaseous state to a liquid state." —The Encyclopedia Britannica 1910

Liquid Air Machine

"A labratory liquid air machine used by Thomson and Joule used to cool hydrogen from a gaseous state…