Saturday 19th May 1787

The Maryland House of Delegates (US) issued a patent to Oliver Evans for his high pressure steam engine. He continued to work on this for the next several years, envisioning both a stationary engine for industrial purposes and an engine for land and water transport. In 1801 he built in Philadelphia a stationary engine that turned a rotary crusher to produce pulverized limestone for agricultural purposes. The engine that became associated with his name was an original adaptation of the existing steam engine; Evans placed both the cylinder and the crankshaft at the same end of the beam instead of at opposite ends, as had been done previously. This greatly reduced the weight of the beam. An ingenious linkage, which became world famous as the Evans straight-line linkage, made the new arrangement feasible. He saw at once the potential of such an engine for road transportation but was unable to persuade the authorities to permit its use on the Pennsylvania Turnpike—not unnaturally, since it might well have frightened the horses, which at that time provided the main form of transport. Within a few years he had engines doing several other kinds of work, including sowing grain, driving sawmills and boring machines, and powering a dredge to clear the Philadelphia water frontage. Completed by June 1805, his new type of steam-engine scow, called the Orukter Amphibolos, or Amphibious Digger, was 30 feet (9 m) long by 12 feet (3.7 m) wide. In its machinery it embodied the chain-of-buckets principle of his automatic flour mill. Equipped with wheels, it ran on land as well as on water, making it the first powered road vehicle to operate in the United States.