Evans, Oliver

Oliver Evans, (born Sept. 13, 1755, near Newport, Del. [U.S.]—died April 15, 1819, New York, N.Y.), American inventor who pioneered the high-pressure steam engine (U.S. patent, 1790) and created the first continuous production line (1784).

Evans was apprenticed to a wheelwright at the age of 16. Observing the trick of a blacksmith’s boy who used the propellant force of steam in a gun, he began to investigate ways to harness steam for propulsion. Before he could successfully pursue this line of research, however, he became involved with a number of other industrial problems. Carding, or combing, fibres to prepare them for spinning was a laborious process constituting a bottleneck in the newly mechanized production of textiles. To speed this operation Evans invented a machine that cut and mounted 1,000 wire teeth per minute on leather, the teeth serving as an improved carding device.

In 1784, at the age of 29, he attacked another major industrial production problem, the age-old process of grinding grain. Building a factory outside Philadelphia and adapting five machines, including conveyors, elevators, and weighing scales, he created a production line in which all movement throughout the mill was automatic. Labour was required only to set the mill in motion; power was supplied by waterwheels, and grain was fed in at one end, passed by a system of conveyors and chutes through the stages of milling and refining, and emerged at the other end as finished flour. The system, which reduced costs by 50 percent according to Evans’ calculations, much later was widely copied in American flour milling.

When Evans applied for patent protection, first to state governments (1787) and later to the new U.S. Patent Office (1790), he added a third invention, 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.

In 1806 Evans began to develop his noted Mars Iron Works, where, over the next 10 years, he made more than 100 steam engines that were used with screw presses for processing cotton, tobacco, and paper. The Navy Yard in Washington, D.C., bought one of Evans’ engines, and, when the War of 1812 broke out, Evans and a partner proposed to build a powerful steam warship with a large gun at the bow, thus anticipating John Ericsson’s Monitor of 50 years later; but the proposal was not accepted.

Evans’ last great work, completed in 1817, was a 24-horsepower high-pressure engine for a waterworks. He died shortly after a disastrous fire that destroyed his Mars Iron Works, including his valuable patterns and molds.

His Young Mill-Wright and Miller’s Guide, which he had written in 1792, continued to sell and had gone through 15 editions by 1860. In another work, The Abortion of the Young Steam Engineer’s Guide (1805), he forecast the need for government subsidization of technological advances.

Vested interests in horses, as well as poor roads, steep gradients, inadequate springing, and an inadequate technology of materials, hindered the adoption of his ideas for steam engines on roads. Also, because later manufacturers were slow to make use of his innovative manufacturing techniques, Evans was long a somewhat neglected figure. More recently, however, in the allocation of priorities for the development of the high-pressure steam engine, the simultaneity of Evans’ work with that of the British genius Richard Trevithick has been established, and historians have accorded proper credit for his pioneering of the assembly line.