A beam engine is a type of steam engine where a pivoted overhead beam is used to apply the force from a vertical piston to a vertical connecting rod. This configuration, with the engine directly driving a pump, was first used by Thomas Newcomen around 1705 to remove water from mines in Cornwall. The efficiency of the engines was improved by engineers including James Watt who added a condenser, Jonathan Hornblower and Arthur Woolf who compounded the cylinders, and William McNaught (Glasgow) who devised a method of compounding an existing engine. Beam engines were first used to pump water out of mines or into canals, but could be used to pump water to supplement the flow for a waterwheel powering a mill.
The rotative beam engine is a later design of beam engine where the connecting rod drives a flywheel, by means of a crank (or, historically, by means of a sun and planet gear). These beam engines could be used to directly power the line-shafting in a mill. They also could be used to power steam ships.
The first beam engines were water-powered, and used to pump water from mines. A 'preserved' example may be seen at Wanlockhead, in Scotland.
Beam engines were extensively used to power pumps on the English canal system when it was expanded by means of locks early in the Industrial Revolution, and also to drain water from mines in the same period, and as winding engines.
The first steam-powered beam engine was developed by Thomas Newcomen. The Newcomen steam engine was adopted by many mines in Cornwall and elsewhere, but it was relatively inefficient and consumed a large quantity of fuel. James Watt resolved the main inefficiencies of the Newcomen engine in his Watt steam engine, and these beam engines were used commercially in much larger numbers.
Watt held patents on key aspects of his engine's design, and it was not until these patents expired that others could develop modifications to improve it. The beam engine was considerably improved and enlarged in the tin- and copper-rich areas of south west England, which enabled the draining of the deep mines that existed there. Consequently the Cornish beam engines became world famous, as they remain the most massive beam engines ever constructed.