312 CONCERNING THE StEAM ENGINE, 



propcfed a pifton fill the capacity of this tube, fo as to havie no air under the 

 Uonr""^'"^"" P^^°" *•" ^^P'" continues to give reafons like a man of great 

 underftanding ; but as there mufl be plates and defcriptions 

 to explain the whole, I fliall fay no more on the fuhje6t, but 

 only add, that the do6lor did his bell to obtain his tind in 

 another manner. He fliews that, with " A little water 

 changed into fteam by means of fire, we can have an elaftic 

 power like air ; but that it totally difappears when chilled, 

 and changes into water; by which means he perc^ved, that 

 he could contrive a machine in fuch a manner, that, with a 

 little fire, he would be able, at a fmall expence, to have a 

 perfed vacuum, which could not be obtained with gun-> 

 powder.'' Among various contrivances, this appeared to 

 anfwer the befl. In the work itfelf a plate of this contri- 

 vance will be given, which, however, is not to be compared 

 to what has been invented fi.nce Papin, by men who had never 

 heard of him, and were altogether much inferior to him in 

 theoretical and pra6lical philofophy. 

 Capt Savery, In 1699, a remarkable year for the honour of Englifii in- 

 * ^^' genuity. Captain Savery fhewed to the Royal Society an en- 



gine which raifed water by means of the expanfion and con- 

 denfation of fleam ; he publifhed a little treatife, which he 

 named " 'The Miners* Friend ;'' the defcription of this engine 

 is to be feen in Harris's Didionary of Arts, &c. printed in 

 London, 1 7 04*. This learned man fays of Savery 's engine, 

 " that with little art it can be kept in adionaslong as one will, 

 and that it cannot be hurt but by ftupidity and negligence." 

 Harris looked on this invention of Savery's to be one of the 

 mod ingenious combinations that had ever been made in hy- 

 draulics, and I may add, that it is furprifing that a feafaring 

 gentleman, in all likelihood little ufed to the working of 

 metals, fhould have brought his invention to the perfedion he 

 left it in. 



• It is feen that PapIn is the firft that thought of a pifton to be 

 applied in fire machinery, though it was but in a tube about two 

 inches diameter, yet it ihewed the utility ofpiftons, which the an- 

 cient Greeks knew as well as the moderns, being one of the moft 

 fimple inventions in hydraulics, as maybe feen in Vitruvius, fpeak- 

 ing of the pumps of Ctellbus fcr the forcing water to a great 

 |iei§ht. 



In 



