This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
In 1837 the American blacksmith Thomas Davenport, working with his wife Emily Davenport, patented a commutated motor that reached six hundred revolutions per minute and could drive machine tools and even a small printing press. It was the first motor built with a shop, not a laboratory, in mind, and it still fell short of what industry needed: without a way to hold a steady speed under a changing load, an electric motor could not replace the belts and shafts a factory already trusted. That problem waited until 1886, when Frank Julian Sprague built the first motor that stayed at a nearly constant speed no matter how hard it was worked, the advance that finally let a factory place power wherever a machine stood rather than wherever a line shaft could reach. Sprague did not stop at the factory floor. In 1887 and 1888 he built the first successful electric streetcar system, carrying his own motor design out of the workshop and into the street, and from there into the subway. The distance between Jacobi's fourteen-passenger boat in 1834 and Sprague's city transit system in 1888 is the distance between a proof that an idea works and a proof that it pays.