HEAT OR CALORIC. 



(W.) OF THE STEAM ENGINE. Dr. Hare. 



The principle of Savarifs Steam Engine illustrated, 



i 



" A matrass, situated as in the above figure, and containing a small 

 quantity of water, being subjected to the flame of a lamp, the water 

 will soon, by boiling, fill the matrass with steam. When this is ac- 

 complished, bubbles of air will cease to escape from the neck of the' 

 matrass, through the water in the vase." 



"The apparatus being thus prepared, on removing the lamp, the 

 water of the vase will quickly rush into the vacuity, in the matrass, 

 arising from the condensation of the steam." 



Of Savary' s Engine.* 



"The celebrated engine of Savary, which led to the invention of 

 that of Newcomen, and finally to the almost perfect machine of Bol- 

 ton and Watt, consisted essentially of a chamber in which steam, 

 after being introduced from a boiler, was condensed by a jet of cold 

 water, as in the experiment above described." 



"Just before the condensation of the steam, the communication 

 with the boiler was cut off, and a cock or valve, was opened in a pipe 

 descending into a reservoir of cold water. The chamber was con- 

 sequently filled with water, which was expelled through an aperture 

 opened for the purpose, by allowing the steam to enter again above 

 the water. The aperture through which the water escaped, and 

 that through which the steam entered, being closed simultaneously, 

 the operation of condensing the steam and filling the chamber with 



* The Marquis of Worcester in 1663 published in his book (whimsically entitled,; 

 The Century of Inventions, an obscure hint of the contrivance, which Savary car- 

 ried into effect in 166& 



