The First of a New Generation of Engines

The engines of the eighteenth- century had all been powered by the weight of the earth’s atmosphere, acting against a vacuum which had been created on the underside of the piston by the condensation of steam, and were then classified as atmospheric engines. Richard Trevithick (1771-1833) a Cornish engineer, designed the first of these engines which used steam at a high pressure directly from the boiler,  this became known as ‘strong steam’. The Trevithick engine was small and compact without the complexity of the atmospheric engines designed by Newcomen and Watt.

The Lambeth Engine

This is a 1/10 scale model, of an engine designed in 1804 by Richard Trevithick which was installed to drive the machinery of a dye house, at Lambeth London. It was one of the first engines, to operate with the steam produced, at a high pressure. Throughout the eighteenth century, engines were powered by a vacuum. This vacuum had been created by condensation of low-pressure steam. The powering cylinder of this engine is also a new innovation, as it is positioned horizontally. It is the first of the high-speed horizontal engines. This model was made from details documented in an early nineteenth- century manuscript, which was first published in 1970. The drawing shown here was taken from this manuscript.

The Engine Details

The boiler was six feet in diameter and was cast from iron at Abraham Darby’s foundry in Coalbrookdale.

The double acting cylinder was eight inches in diameter, and the piston made a working stroke of 48 inches. This engine was rated at six horsepower, and made 24 revolutions per minute, with a working boiler pressure of approximately 45 pounds per square inch.

This model is constructed from natural materials, there are 8,200 ceramic bricks, in the building, and the floor is constructed from slivers of micaceous sandstone. The tiles needed to complete the roof are shown here.

Perhaps, one point of interest to the model engineer is the boiler; which has a wall thickness of 4.5 mm and is machined from a solid piece of mild steel. The model will steam, but for demonstration purposes, it is run on compressed air.

A High Pressure Steam Engine

This is a model of a typical small beam engine. Engines of this type would have been used to provide rotary power for factories in the 1860s. The model does not represent any known prototype, but has been built to show how engines became smaller and their power output increased when steam at a high pressure was used to drive their double acting cylinders.

A vertical boiler provides the steam to drive this engine, which was originally heated by coal, but in its miniature form is now heated by a gas burner.

Francis Thompson’s Arnold Mill Engine of 1797 and Richard Trevithick’s Lambeth Engine of 1804 are described in detail in my book entitled

MECHANICAL WONDERS

THE ENGINES THAT CHANGED THE WORLD