Manchester Memoirs, Vol. lix. (191 5), No. 11. 13 



single vessel which served both as boiler and reservoir, 

 the heated water itself being forced upwards. 



EDWARD SOMERSET, 2nd Marquis of Worcester, 

 conceived and perhaps constructed a steam apparatus in- 

 tended to raise water to a higher level. The description 

 of this apparatus is, unfortunately, rather obscure. It 

 probably worked in a manner similar to that of della 

 Porta, but comprised two chambers of displacement, 

 which were emptied alternately by the vapour pressure, 

 in such a way that the other vessel refilled itself automa- 

 tically with a fresh quantity of water. The use of two 

 vessels acting alternately, was a distinct advance. 



A new improvement was introduced by THOMAS 

 Savery (1650 — 1715) and patented in 1698. His 

 machine was much more complicated than all the preced- 

 ing ones. It consisted in a boiler into which the water, 

 already heated, was driven by means of a steam jet 

 similar to that of Salomon de Caus. The steam generated 

 in the boiler was admitted to a receiver full of water, and 

 expelled the water through a tube after the principle of 

 della Porta. The steam was afterwards condensed in the 

 receiver by the application of cold water to the exterior, 

 and through the agency of the vacuum produced a fresh 

 quantity of water was drawn up through another tube. 

 The receiver is thus filled again, a fresh jet of steam 

 expells the contents, and the action continues. This 

 arrangement was the application of an idea suggested by 

 della Porta, The use of two receivers acting alternately 

 was borrowed from Somerset. 



It is clear then that Savery made use of the inventions 

 of his predecessors. What there was really new was the 

 adroit combination of these inventions, the artificial con- 

 densation of the vapour, and the addition of tubes and 

 taps connecting the different parts. Now that the steam 



