- Historic Sites
October 1992 | Volume 43, Issue 6
For the rest of his life Evans was to rail ill-temperedly against the human tendency to stick with the status quo and to bemoan the fact that fate had made him a genius in a world where geniuses were not appreciated. “He that studies and writes on the improvement of the arts and sciences labours to benefit generations yet unborn,” Evans wrote at a particularly gloomy period of his life, “for it is not probable that his contemporaries will pay any attention to him...; therefore improvements progress so slowly.”
Evans patented his flour-mill process in several states and, after the new federal Constitution went into effect, received only the third patent the new government issued. (The first patents were signed by Washington and two members of his new cabinet, including another prolific American inventor, Secretary of State Thomas Jefferson. Jefferson must have been impressed as a few years later he would set up an Evans type of flour mill at one of his own plantations and paid Evans an eighty-dollar license fee for the privilege. George Washington, also always receptive to new technology, bought a license for his mill at Mount Vernon as well.)
Despite Evans’s grumpy attitude about people’s reluctance to change, the Evans process relentlessly spread through the industry over the next twenty years while its essential idea spread to other industries as well. Its success was greatly helped by a book Evans wrote called The Young Mill-Wright and Miller’s Guide. A how-to book on building and running flour mills, it would have fully fifteen editions, the last printed on the eve of the Civil War, forty years after the author’s death.
Although his flour-mill inventions were a solid success, the license fees were not yet enough to earn a living, and Evans moved to Philadelphia and became a merchant, specializing in flour-mill equipment. But his restless mind was turning back to his adolescent passion: steam.
When he first learned about Watt’s engine, Evans had dreamed of building a steam carriage. But Watt’s engine did not produce anywhere near enough power to move itself, let alone a carriage. The Watt engine operated on low pressure and worked at what today seems an almost surreally slow pace, about twelve cycles per minute. In the Watt engine steam pushed the piston to the bottom of the cylinder and then was drawn off and condensed, creating a vacuum that sucked the piston back up.
None of Evans’s devices were entirely new; what was stunningly new was his conception of an integrated, automatic, industrial process.
Evans developed an engine using high-pressure steam that not only pushed the piston down but pushed it back up as well. Watt’s separate condenser was dispensed with. The result was a steam engine that was far smaller than Watt’s and yet produced far more power per unit of weight because it operated at many times the speed. Evans’s first engine, built in 1802, had a cylinder about six inches in diameter and eighteen inches long. It produced about five horsepower. The two great Watt-type engines that had been installed the year before to power the Philadelphia waterworks at Center Square, in contrast, each had a cylinder diameter of thirty-two inches and a stroke of six feet. Yet each produced only twelve horsepower.
Evans set his engine to stationary work, but soon returned to his steam-carriage idea. He was commissioned to build a steam dredge for Philadelphia Harbor. He did so near his shop, which was about a mile from the Schuylkill River up Market Street. The vessel, improbably named the Orukter Amphibolos, was twelve feet wide and thirty feet long. It weighed fully seventeen tons. To get it to the river, he put it on two sets of wheels, attached the engine to one axle with a chain drive, and proceeded down Market Street “with a gentle motion.”
When he got to Central Square, he gave a demonstration, circling several times the waterworks located there. He was, of course, both literally and metaphorically running rings around Watt’s low-pressure engines with his high-pressure one.
The demonstration over, the first land vehicle in America to move by means other than muscle power tootled off down Market Street toward the river, dropped its wheels, and entered both the Schuylkill and the oblivion that is the fate of dredges.
But its engine did not. Further refined and enlarged, it proved the perfect power source for the steamboats that were soon operating in the shallow and treacherous waters of the Mississippi River system as well as myriad industrial uses and, later, the early railroads. Together with the licensing fees of his flour mill, it made Evans’s old age a prosperous one.
Oliver Evans, still grumpy and convinced of the stupidity of his fellow man despite his prosperity, pointed the way to the nineteenth century. His fellow man, not so stupid after all, took it from there.