400 Addllioiial Note$, 



of the equatorial diameter of the sphere ; the sphere was supplfetl 

 \vith steam by a pipe communicating with a pan of boiling water, 

 and entering tlie sphere at One of its poles. 



" A French writer, about the year l(i30, describes a method of 

 raising water to the upper part ot" a house, by filling a chamber 

 with steam, and suffering it to condense of itself) but it seems to 

 have been mere theorj^, as his method was scarcely practicable as he 

 describes it. In 1655^ the marquis of Worcester mentions a me- 

 thod of raising water by lire, in his Century of Inventions ; but he 

 seems only to have availed himself of the expansive force, and not 

 to have known the advantages arising from condensing the steana 

 by an injection of cold water. This latter and most important im- 

 provement seems to have been made by capt. Savary^ some time 

 prior to the year lOQS, for in that year his patent, for the use of 

 that invention, was conhrmed by act of parliament. This gentle- 

 man appears to have been the first who reduced the machine to 

 practice, and exhibited it in a useful form. His metliod con- 

 sisted only in expelling the air from a vessel by steam ; condens- 

 ing the ste-am by an injection of cold water, which making a vr- 

 cuum, tlie pressure of the atmosphere forced the water to ascend 

 hito the steam- vessel through a pipe of 24 or 26 feet high; and, by 

 the admission of dense steam from the boiler, forcing the water in 

 the stcam-vesscl to ascend to the height desired. This construc- 

 tion was defective, because it required very strong vessels to resist 

 the force of the steam, and because an enormous quantity of steam 

 was condensed by coming into contact with the cold water in tlie 

 steam- vessel. 



" About, or soon after that time, M. Papin attempted a steam- 

 engine on similar principles, but rather more defective in its 

 construction. 



*' The ru'xt improvement was made ver)' soon afterwards by 

 Messrs. Xewcomcn and Cawley, of Dartmouth : it consisted in 

 employing for the steam- vessel a hollow cylinder, shut at bottom 

 and open at top, furnished with a piston sliding easily up and 

 down in it, and made tight by oakum or hemp, and covered 

 with water. This piston is suspended by chains from one end of 

 a beam, moveable upon an axis in the middle of its length : to the 

 other end of this beam are suspended the pump-rods. 



"The danger of bursting the vessels was avoided in tliis ma- 

 chine ; as^ however high the water was to be raised, it was not 

 necessary to increase the density of the steam, but only to enlarge 

 the diameter of the cylinder. 



