CATALOG OF THE MECHANICAL COLLECTIONS 25 



1630), Italian physicists and mathematicians, established some of the 

 "capabilities" of steam, namely, that steam is evaporated water ; that 

 it returns to water when cooled; and that a vacuum is formed by 

 condensing steam in a closed vessel. De Caus built a fountain from 

 which water was forced by the pressure of steam. This knowledge 

 plus that derived from the work of Galileo (1564-1642) and Torri- 

 celli (1608-1647) in Italy; Pascal (1623-1662) in France; and von 

 Guericke (1602-1686) in Germany, whereby the true nature of the 

 vacuum was demonstrated, formed the background for the modern 

 development of the steam engine. Edward Somerset (1601-1667), 

 second Marquis of Worcester, is thought to have built at Vauxhill, 

 England, about 1663-1669, the first useful and practical steam engine. 

 This engine consisted of a high-pressure boiler into which water was 

 forced by atmospheric pressure, after the contained steam had con- 

 densed, and from which the water was then discharged by steam 

 pressure, raising the water, in all, about 40 feet. This method was 

 extensively applied by Thomas Savery (1650-1715), who patented 

 a similar apparatus in 1698 and built several such steam engines to 

 pump water from mines. 



In the meantime Huygens (1629-1695) had, about 1680, attempted 

 an atmospheric (explosive) engine, and Papin (1647-1712) in 1690 

 demonstrated the suitability of using steam to produce a vacuum in 

 a piston engine. It remained for Thomas Newcomen (1663-1729), 

 however, to perfect about 1712 an atmospheric steam engine in which 

 a vacuum could be formed repeatedly and regularly in a cylinder 

 beneath a reciprocating piston. Newcomen later (1713 or 1718) pro- 

 vided a valve gear to make the engine completely automatic in its 

 operation. This engine supplied, for the first time in history, large 

 units of cheap and reliable power, and is the form from which the 

 growth of the modern steam engine is continuously traced. The im- 

 portance of the Newcomen engine cannot be overestimated. 



James Watt (1736-1819) became interested in the steam engine 

 when he was employed, about 1763, to repair a working model of a 

 Newcomen engine. His great work consisted in devising all the 

 numerous changes in the Newcomen engine that were necessary to 

 convert it, in principle at least, to the steam engine of the present 

 day. Watt invented the separate condenser, the condenser air pump, 

 the steam- jacketed cylinder, mechanisms for converting reciprocating 

 motion to rotary motion, and the double-acting cylinder. He was the 

 first to use "high" pressure steam and steam expansively. The results 

 of Watt's work are best shown by a comparison of the efiiciency of a 

 Newcomen engine of 1767 (three years after Watt began his work) 

 with that of a Watt engine of 1800. The Newcomen engine produced 

 4.3 million foot-pounds of work (water pumped) for every 112 



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