T. Savery, D. Papin, T. Newcomen 101 



a piston, but abandoned the idea in favour of a modified 

 form of Savery 's engine. 



During his stay in England, Papin took an active part 

 in the Proceedings of the Royal Society, and in 1684 was 

 appointed temporary curator of that body with a salary 

 of 30, in consideration of which he was required to pro- 

 duce an experiment at each meeting of the Society. He 

 had invented a so-called " bone-digester," to which Evelyn 

 in his diary refers in these terms : " The hardest bones of 

 beef itself and mutton were made as soft as cheese, without 

 water or other liquor, and with less than eight ounces of 

 coal, producing an incredible quantity of gravy; and, for 

 close of all, a jelly made of the bones of beef, the best for 

 clearness and good relish, and the most delicious that I 

 have ever seen or tasted." Papin kept up his correspondence 

 with the Royal Society after settling in Germany, sub- 

 mitting to them a proposal to apply a steam engine to the 

 propulsion of ships, and asking for a grant of 15 for his 

 " expense, time and pain " in putting his ideas to the test. 

 Papin is also credited with the invention of the safety 

 vaive. 



The next successful step in the construction of steam 

 engines was taken by Thomas Newcomen (1663-1729), an 

 ironmonger of Dartmouth, who seems to have entered into 

 correspondence on the subject with Robert Hooke, and, 

 together with Cawley, another tradesman of his native 

 town, produced a machine which in several ways was better 

 than its predecessors. He introduced a cylinder with a 

 piston that could be raised by the pressure of steam, the 

 piston rod being mechanically connected with a pumping 

 arrangement. The steam was condensed in the cylinder 

 itself by a jet of water, and the work was mainly performed 

 in the downward stroke, when the atmospheric pressure of 

 air pressed the piston down into the vacuum formed inside 

 by the condensation of steam. Newcomen's engines came 

 into general use for the pumping of water. 



In all the attempts made so far, no consideration is given 

 to the economical use of fuel, a disadvantage which was 

 severely complained of by those who used the engines. 

 A new era began with the work of James Watt (1736-1819 



