Steam Engine

Throughout all of this development and improvement of the steam engine, no one really knew the science behind it. Basically, all of this work had been accomplished on an empirical basis without reference to any theory. It was not until 1824 that this situation changed with the publication of Reflexions sur La Puissance Motrice du Feu by the French physicist, Nicolas Leonard Sadi Carnot (1796-1832). In his book On the Motive Power of Fire, Carnot founded the science of thermodynamics (or heat movement) and was the first to consider quantitatively the manner in which heat and work are related. Defining work as "weight lifted through a height," he attempted to determine how efficient or how much "work" a Watt engine could produce. Carnot was able to prove that there was a maximum theoretical limit to the efficiency of any engine, and that this depended upon the temperature difference in the engine. He showed that for high efficiency, steam must pass through a wide temperature range as it expands within the engine. Highest efficiency is achieved by using a low condenser temperature and a high boiler pressure. Steam was successfully adapted to power boats in 1802 and railways in 1829. Later, some of the first automobiles were powered by steam, and in the 1880s, the English engineer Charles A. Parsons (1854-1931) produced the first steam turbine. This high-powered, highly efficient turbine could produce not only mechanical energy but electrical energy as well. By 1900, the steam engine had evolved into a highly sophisticated and powerful engine that propelled huge ships in the oceans and ran turbogenerators that supplied electricity.

Once the dominant power source, steam engines eventually declined in popularity as other power sources became available. Although there were more than 60,000 steam cars made in the U. S. between 1897 and 1927, the steam engine eventually gave way to the internal combustion engine for vehicle propulsion. Today, interest in steam has revived somewhat as improvements make it increasingly efficient and its low-pollution factors make it more attractive.