SECT . 



THE STEAM ENGINE. 25 



hotd out an inducement to speculative men to attempt to remove them, and among 

 these Blakey was one of the most sanguine. He obtained, in 1766, a patent for a 

 new mode of constructing Savery's engine, by using two receivers, one placed over 

 the other, with a pipe of communication between them. The contact of the steam 

 and water was to be prevented by a stratum of oil, forming a species of fluid 

 floating piston. He further proposed to admit air to occupy the place between the 

 steam and water, so as to prevent condensation during the process of forcing : both 

 methods inferior to the floating piston of Papin. Blakey had, however, sufficient 

 art to persuade the public that he had made a valuable discovery, and to get 

 Ferguson, the lecturer, to show off its advantages by a steam fountain. 1 In practice 

 his method was found to be worthless. 



In generating steam, Blakey seems to have first proposed cylindrical tubes for 

 boilers, the description of which he published in 1774. He was also the author of 

 a pamphlet entitled, ' A Short Historical Account of the Invention, Theory, and 

 Practice of Fire Machinery,' printed in London in 1793, which was chiefly filled 

 with short notices of his own labours on the subject, now of no interest. 







1769. JAMES WATT, LL.D. F.R.S. ; born 1735, died 1819. 



26. The commencement of the researches of Mr. Watt appears to have been 

 in 1764, two years after Dr. Black began to teach his doctrines regarding heat. 

 Mr. Watt began by making experiments on the elastic force and bulk of steam, 

 and gradually developed those principles which form the basis of his valuable 

 improvements on the steam engine ; but he did not so far mature his plans as to 

 apply for a patent till 1768, which was enrolled in 1769. The specification is brief, 

 and not illustrated by figures ; hence I will give it entire, and then distinguish the 

 principles and methods of construction which had not been anticipated. 



Mr. Watt's patent of 1769 was for his ' Methods of Lessening the Consumption 

 of Steam, and consequently of Fuel in Fire Engines;' and his specification is as 

 follows : " First ; that vessel in which the powers of steam are to be employed to 

 work the engine, which is called the cylinder in common fire engines, and which I 

 call the steam vessel, must, during the whole time the engine is at work, be kept 

 as hot as the steam that enters it ; first, by enclosing it in a case of wood, or any 

 other materials that transmit heat slowly ; secondly, by surrounding it with steam, 

 or other heated bodies ; and, thirdly, by suffering neither water, nor any other 

 substance colder than the steam, to enter or touch it during that time. Secondly ; 

 in engines that are to be worked wholly or partially by condensation of steam, the 



1 Ferguson's Lectures, vol. i. p. 312. 

 



