Audioscripts unit 1 The Steam Engine

It is tempting to think of the car or the airplane as among the most important inventions of the millennium. But these were merely evolutionary refinements of the steam engine – the first machine to convert burning fuel into mechanical energy on a large scale. The first steam engines were powered by wood, and later ones by coal. Steam engines transformed the industrial world as few other technologies have. This invention liberated people from the limitations of their own muscles and those of beasts of burden. It made possible the factories that drove the Industrial Revolution. And it was at the heart of the first form of high-speed mechanized transportation: the locomotive.

The steam engine is a classic example of an invention that came about in stages. In 1698 English engineer Thomas Savery developed a water pump that used steam from a boiler for its power. Savery obtained a broad patent on the idea, even though his engine design never proved to be very useful. This was followed by a significantly more effective steam engine, built by English blacksmith Thomas Newcomen in 1712. Newcomen's device was also used primarily to pump water from coal mines. However, Scottish engineer James Watt is the individual most commonly cited as the inventor of the steam engine. His machine, patented in 1769, was vastly more efficient than were previous devices, chiefly because of its separate cooling chamber for condensed steam. Watt added other improvements, such as oil lubrication and insulation. He also designed a system of gears that translated the up-and-down motion of the steam-driven piston into rotary motion, which was more useful in driving machinery.

Watt's engine freed factories from their dependence on water power and gave a huge advantage to nations with ready supplies of coal. Britain's great reserves of coal fueled the expansion of the British Empire in the 18th and 19th centuries. Steam-powered railroad trains played a huge role in industrialization and trade and were vital to the westward expansion of the United States. Internal-combustion engines and electrical generating stations have since taken over most of the jobs once performed by steam, but these creations had to stand on the shoulders of the steam engine.

From Encyclopædia Britannica

Unit 2 The Watt engine.

While repairing a model Newcomen steam engine in 1764 Watt was impressed by its waste of steam. In May 1765, after wrestling with the problem of improving it, he suddenly came upon a solution — the separate condenser, his first and greatest invention. Watt had realized that the loss of latent heat (the heat involved in changing the state of a substance — e.g., solid or liquid) was the worst defect of the Newcomen engine and that therefore condensation must be effected in a chamber distinct from the cylinder but connected to it. Meanwhile, Watt in 1766 became a land surveyor; for the next eight years he was continuously busy marking out routes for canals in Scotland, work that prevented his making further progress with the steam engine. After Roebuck went bankrupt in 1772, Matthew Boulton, the manufacturer of the Soho Works in Birmingham, took over a share in Watt's patent. Bored with surveying and with Scotland, Watt immigrated to Birmingham in 1774.

After Watt's patent was extended by an act of Parliament, he and Boulton in 1775 began a partnership that lasted 25 years. Boulton's financial support made possible rapid progress with the engine. In 1776 two engines were installed, one for pumping water in a Staffordshire colliery, the other for blowing air into the furnaces of John Wilkinson, the famous ironmaster. During the next five years, until 1781, Watt spent long periods in Cornwall, where he installed and supervised numerous pumping engines for the copper and tin mines, the managers of which wanted to reduce fuel costs. In the following year Boulton, foreseeing a new market in the corn, malt, and cotton mills, urged Watt to invent a rotary motion for the steam engine, to replace the reciprocating action of the original. He did this in 1781 with his so-called sun-and-planet gear, by means of which a shaft produced two revolutions for each cycle of the engine. In 1782, at the height of his inventive powers, he patented the double-acting engine, in which the piston pushed as well as pulled. The engine required a new method of rigidly connecting the piston to the beam. He solved this problem in 1784 with his invention of the parallel motion — an arrangement of connected rods that guided the piston rod in a perpendicular motion—which he described as “one of the most ingenious, simple pieces of mechanism I have contrived.” Four years later his application of the centrifugal governor for automatic control of the speed of the engine, at Boulton's suggestion, and in 1790 his invention of a pressure gauge, virtually completed the Watt engine.

From Encyclopædia Britannica