WATT. 353 



observations of men at any period. The ancients 

 accordingly were so far acquainted with it as to have 

 constructed an instrument, the seolipile, composed of a 

 metallic ball, which, having some water in its bottom, 

 was placed in the fire, and the steam, issuing through a 

 small orifice or tube with great force, could, they con- 

 ceived, blow a fire or even turn the vanes of a mill. No 

 use, however, seems ever to have been made of this philo- 

 sophical toy ; nor does any attention appear to have been 

 paid to steam, as an agent, until 1615, when Salomon de 

 Caus, a French engineer, published a work on ' Moving 

 Forces,' in which he describes a method of raising water 

 by partially heating it, that is, converting a portion of it 

 into steam, and, by its expansive force, driving the rest of 

 the fluid through the tube connected with the reser- 

 voir or chamber.* In 1663 the Marquis of Worcester 

 (known in our political history as Earl of Glamorgan, 

 and as having been employed by Charles I. in 1646 to 

 negotiate with the Irish Catholics) published his 

 ' Century of the Names and Scantlings of Inventions,' 

 of which Mr. Hume, in his ( History' (vol. vii., note o), 

 has been pleased to say that it is "a ridiculous com- 

 pound of lies, chimeras, and impossibilities, showing 

 what might be expected from such a man." The better 



* M. Arago is not entitled to complain of English writers for 

 having " aimed at expunging every French name from this important 

 chapter in the history of science." He says they at once gave up 

 Lord Worcester's claims on discovering that Salomon de Caus had 

 preceded him. Now both Mr. Farey and Mr. Stuart have done 

 ample justice to Caus in their works on the steam engine. As for 

 Lord Worcester, Mr. Stuart (whose history is far from accurate on 

 this point) has both attacked and defended his claims in his several 

 works. 



2 A 



