James Watt and the Steam Engine 

·        James Watt

James Watt was a Scottish inventor and engineer whose improvements to the steam engine were fundamental to the changes made possible by the Industrial Revolution. 

His improved steam engine transformed the one created by Thomas Newcomen in 1712 into a source of power that altered the world of work, and was the key that opened the door to the Industrial Revolution. “The importance of the invention can hardly be overstated--it gave us the modern world.” (Wikipedia)

The most notable improvement to Newcomen’s engine was Watt's 1769 patent for a separate condenser connected to a cylinder by a valve. Unlike Newcomen's engine, Watt's design had a condenser that could be cool while the cylinder was hot. Watt's engine soon became the dominant design for all modern steam engines and helped bring about the Industrial Revolution. (About.com)

Soon after Watt improved the steam engine, he found himself very busy installing them, mostly for pumping water out of mines. 

Watt also made a number of other improvements and modifications to the steam engine. He produced a double acting engine, in which the steam acted alternately on the two sides of the piston. Another improvement was the throttle valve to control the power of the engine, and a centrifugal governor to keep it under control. He described methods for working the steam expansively. He was able to link engines together to make them compound engines.  He also used a steam indicator which produced an informative plot of the pressure in the cylinder against its volume, which he kept as a trade secret.  The invention that Watt was most proud of was the Parallel motion / three-bar linkage which was especially important in double-acting engines. This was patented in 1784. These improvements taken together produced an engine which was up to five times as efficient in its use of fuel as the Newcomen engine.

Because of the danger of exploding boilers and the ongoing issues with leaks, Watt was opposed from the first to the use of high pressure steam--all of his engines used steam at very low pressure.

In 1794 James Watt and Matthew Boulton established what would become a large enterprise, Boulton and Watt, which exclusively manufactured steam engines. By 1824 it had produced 1164 steam engines having a total nominal horsepower of about 26,000.  Boulton proved to be an excellent businessman, and both men eventually made fortunes.

Watt continued to invent other things before and during his semi-retirement. He invented a new method of measuring distances by telescope, a device for copying letters, improvements in the oil lamp, a steam mangle and a machine for copying sculptures. (Wikipedia)