JAMES WATT. 27 



from the well or mine below, exactly as in the common sucking- 

 pump. Having thus raised the water to the level of the boiler, 

 he afterwards allowed it to flow into another vessel, from whence 

 he sent it to a greater height by the same method which had 

 been many years before employed by the Marquis of 

 Worcester, — namely, by making the expansive force of the 

 steam act upon it directly, and so force it up in opposition to 

 its own gravity and the resistance of the atmosphere. 



Savery showed much ingenuity and practical skill in contriv- 

 ing means of facilitating and improving the working of the 

 apparatus which he had devised upon these principles; and 

 many of his engines were erected for supplying gentlemen's 

 houses with water and other purposes, in different parts of the 

 country. The machine also received many improvements after 

 the death of the original inventor. It was considerably simpli- 

 fied, in particular, by Dr. Desaguliers, about the year 17 18; 

 and this gentleman also contrived a method of concentrating 

 the steam by the injection of a small current of cold water into 

 the receiver, instead of the old method employed by Savery, of 

 dashing the water over the outside of the vessel, which cooled 

 it to an unnecessary degree, and occasioned, therefore, a 

 wasteful expenditure of fuel. It was Desaguliers who first 

 introduced the safety-valve into the steam-engine, although 

 Papin had previously suggested such an application of the 

 contrivance. Engines upon Savery's principle have continued 

 to be constructed, down to oui own times ; and, as they can be 

 made at a comparatively small expense, they are found to answer 

 very well in situations where water has to be raised only a short 

 way. This engine is, in fact, merely a combination of the com- 

 mon sucking-pump (except that the requisite vacuum is produced 

 by the condensation of steam, and without the aid of a piston) 



