WATT. 27 



side, for the work is higly creditable to its author's 

 learning and ingenuity, and it undoubtedly contains a 

 proof that he had made one step in advance of Caus 

 towards the use of steam power. His Sixty-eighth 

 Invention is entitled " an admirable and most forcible 

 way to drive up water by fire." He describes his 

 having made a "constant fountain stream of water, 

 raised in the proportion of forty times the quantity of 

 that which he converted into steam ;" and he states 

 that the height to which he raised it was forty feet, 

 clearly showing that it was not on the principle of the 

 sucking-pump, which can only raise water thirty-three 

 feet. He expressly says, that while the atmospheric 

 pressure by which the sucking-pump acts is limited in 

 its operation, the force of steam which he employed 

 " hath no other boundary than the strength of the vessel 

 which contains it." Finally, he seems to have used a 

 cannon as his boiler, which indicates his having tried 

 the experiment on a large scale. The great doubt ex- 

 pressed by M. Arago, whether or not Lord Worcester 

 ever executed the design more or less clearly described 

 in his book, appears to me to have no foundation. The in- 

 ference arising from the description 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 1669 ; and it appears that the Grand Duke 

 " went to see, at Vauxhall, an engine or hydraulic ma- 

 chine invented by the Marquis of Worcester," and the 

 account which he gives of it tallies with Lord Worces- 

 ter's description of his " stupendous water-commanding 

 engine." 



* See also the Marchioness of Worcester's correspondence with her Con- 

 fessor, communicated by the Beaufort family to Mr. Partington for his 

 edition of the " Century." 



