Thursday, January 11, 2018

Is it Steam Engine Time Yet?


In re-reading Alfred Crosby’s Children of the Sun (2006), I was struck by the Rube-Goldberg-like complexity of the first practical steam engine. Thomas Newcomen’s machine, which first went into operation in 1712*, used coal - the remains of Mesozoic plants - to heat water within a large boiler, the steam from which then discharged into a large, cylindrical brass chamber. The steam filled the cylinder with vapor pressure and raised a piston connected to a rocker beam. Then the mechanism cooled the cylinder with a spray of cold water, condensing the steam and creating a vacuum. Atmospheric pressure, whose power Europeans had only discovered a few decades earlier, then pushed the piston back down into the evacuated cylinder and delivered the power stroke to the rocker beam. The cycle then began anew with the refilling and condensation of the engine chamber.
 

Newcomen’s engine (the “Common Engine”) was clumsy and crude by the standards of later inventors, but revolutionary enough in its day: it generated five horsepower in a confined space, using fuel far cheaper than the fodder and upkeep for five living horses. Its two-cycle rocker beam could power a pump capable of draining some of the deepest coal mines in southern England. One feature of the Newcomen engine strikes me as particularly magical: the way it combined all four of the Classical elements to do its work. From the earth came the machine's black and sulfurous** fuel, and to the earth its labor returned. The common air supplied the pressure for the engine's power stroke. Water became the eponymous steam, and cooled that steam to produce the all-important vacuum. Fire generated the steam itself and thereby drove the piston upward. The chartered firm that patented Newcomen's device in 1715 encapsulated in its name the bizarre and contradictory nature of the engineer's experiment: "The Society for Moving Water by Fire." It sounds almost like an alchemists' club. I imagine Isaac Newton, who considered astronomy and astrology of nearly equal interest, would have found its work intriguing if its members weren't so declasse.


*Hellenistic Greeks knew of steam’s power and one or two had built a simple steam engine, but these functioned only as toys. The Greeks had sufficient slaves to discourage their replacement with labor-saving devices.


** I presume it used bituminous coal.

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