All About Engines

James Watt: The Man and his Work 43 and in 1773 Watt entered into partnership with Boulton and made arrangements to have his engines made by his skilled workmen in the works at Soho, Birmingham. Let us now examine a little more closely the nature of Watt’s invention. In the specification of his patent of 1769 lie said : “ My method of lessening the consumption of steam, and consequently fuel, in fire engines con- sists of the following principles : ” First, that vessel, in which the powers of steam are to be employed to work the engine, which is called the cylinder in common fire engines, and which I call the steam vessel, must, during the whole time the vessel is at work, be kept as hot as the steam that enters it ; first, by enclosing it in a case of wood, or any other materials that transmit heat slowly ; secondly, by surrounding it with steam or other heated bodies; and thirdly, by suffering neither water nor any other substance colder than steam to enter or touch it during that time. “ Secondly, in engines that are to be worked wholly or partially by condensation of steam, the steam is to be condensed in vessels distinct from the steam vessels or cylinders, though occasionally com- municating with them; these vessels I call con- densers ; and, whilst the engines are working, these condensers ought at least to be kept as cold as the air in the neighbourhood of the engines, by applica- tion of water or other cold bodies. “ Thirdly, whatever air or other elastic vapour is