WATT. 355 



clearly described in his book appears to me to have no 

 foundation. The inference arising from the descrip- 

 tion seems to remove that doubt ; but we have external 

 evidence more precise and satisfactory still.* The 

 travels in England of the Grand Duke of Tuscany, 

 Cosmo de' Medicis, were written by his Secretary, 

 Magalotti, a man of some scientific eminence ; and a 

 translation into English was published in 1821. The 

 visit to London took place in the year 1 669 ; and it 

 appears that the Grand Duke " went to see, at Vaux- 

 hall, an engine or hydraulic machine invented by the 

 Marquis of Worcester," and the account which he 

 gives of it tallies with Lord Worcester's description of 

 his " stupendous water-commanding engine." 



The account of Lord Worcester is far from being 

 clear and distinct, and nothing appears to have resulted 

 from his suggestions. In 1690, Papin, an eminent and 

 able French engineer, settled in London, and author 

 of the digester which goes under his name, pub- 

 lished a work in which he showed that he had made 

 two most important steps in the use of steam. Caus 

 and Worcester had applied the force directly to the 

 body which it was intended to move ; and it was 

 evident that, while that was a condition of its use, 

 very limited bounds must confine the operation. 

 But Papin, observing the use of the piston in a com- 

 mon sucking-pump, applied this to the steam machine, 

 making it work in the cylinder, and be the medium of 



* See also the Marchioness of Worcester's correspondence with 

 her Confessor, communicated by the Beaufort family to Mr. Par- 

 tington for his edition of the ' Century,' 



2 A 2 



