The Watt steam engine design became synonymous with steam engines, and it was many years before significantly new designs began to replace the basic Watt design.
A late version of a Watt double-acting steam engine, built by D. Napier & Son (London) in 1832, now in the lobby of the Superior Technical School of Industrial Engineers of the UPM (Madrid). Steam engines of this kind propelled the Industrial Revolution in Great Britain and the world.
The model Newcomen engine upon which Watt experimented
The major components of a Watt pumping engine
Watt's parallel motion on a pumping engine
Newcomen atmospheric engine
The atmospheric engine was invented by Thomas Newcomen in 1712, and is often referred to as the Newcomen fire engine or simply as a Newcomen engine. The engine was operated by condensing steam drawn into the cylinder, thereby creating a partial vacuum which allowed the atmospheric pressure to push the piston into the cylinder. It was historically significant as the first practical device to harness steam to produce mechanical work. Newcomen engines were used throughout Britain and Europe, principally to pump water out of mines. Hundreds were constructed throughout the 18th century.
Newcomen engine as depicted on a 2/- note of the Province of New York, 1775
Pencil sketch of Newcomen steam engine as improved by Smeaton, from Popular Science monthly circa 1877
Newcomen-style engine at the Elsecar Heritage Centre, in 2006
Caprington Colliery Newcomen engine in the National Museum of Scotland.