4iO Hijlorical Incidents and Remai-h coticci'iiing 



tical pipe r G. Tlicfc communications are made between two valves II I and K L open- 

 ing upwards ; and the effetl is as follows : Imagine the upper part of the pipe to be filled 

 with water for the purpofe of rendering the valves tight, and let the cock D be turned. 

 'J'he ilcam from the boiler, being lighter than the air included in the vefl"e> B, expels that 

 air, -which, not being permitted to pafs through the valve H, iflucs upwards tlirougli I. In 

 this fituation, let the cock D be fliut, and cold water be thrown upon B, or, which is much 

 better, fpouted into it; and the fteam will become condenfed, and leave ar. empty fpace into 

 which the preflure of the atmofphere at F will force the water upwards through the valve 

 H. While this is performing, the cock E is to be opened, and the air from the vciTel C ex- 

 pelled by the fteam in the fame manner. This is the regular feries of operations, and is 

 repeated a fecond time by fliutiing the cock E, cooling the vclFcl C, and opening the cock 

 I>. By tliefc means the water rifes from F into the veflcl C, while the fleam from the boiler 

 prefles the water out of B, through the valve I, to G. The whole proccfs therefore, fimpli- 

 fied by attending to one of the veflels only, is found to confifl in expelling the air by fteam ; 

 forming a vacuum by condenfation into which the water rifes, and then forcing that water 

 upwards by new fteam, which, being condenfed as before, is replaced by new water ; and 

 fo forth. 



To what practical extent the experiments of the INIarquis of Worccfter were carried, 

 does not appear ; but it was near the end ^f the feventecnth century, when Captain Savery 

 propofed this engine as an invention of his own, for r.iifing water and draining mines. 

 Prony, in his Architefture Hydraulique, i. 564, fays, he publiftied his Miner's Friend about 

 1699. Defaguliers, in his Courfe of Experimental Philofophy, 3d edition, ii. 465, does 

 not fcruple toaJlirm, that Savery had this invention from the Marquis of Worcelter'S book ;. 

 but has not, it muft be confeflcd, given to his aflertion all the proof it might require. He 

 fays, that Savery bouglit up all the copies of the Century of Inventions which he could 

 procure, and burned them ; and that he ufed to relate a Itory as the firft hint of his inven- 

 tion : that having drank a ilafk of Florence at a tavern, and thrown the enpty fiaflc upon 

 the fire, he called for a bafon of water to wa(h his hands ; and perceiving the little wine 

 left in the tlalk had filled it with fteam, he took it by the neck and plunged its mouth in 

 the water, wliich was immediately driven up by the preflure of the air. On this incident. 

 Dr. D. rerparks, that it could not have fo happened ; becaufc when he himfelf had repeated 

 tlie experiment by bc'ling half a glafs of wine in a flafk, and, putting on a thick glove to 

 defend his hand, had plunged its mouth beneath the furface of water, the preflure of the 

 atmofphere was fo ftrong as to beat the flaflc out of his hand againft the cieling — a circum- 

 ftancc with which he does not doubt but that the Captain would have cmbelliflied his tale. 

 if he had made t!ie experiment. 



It appears to me, nevcrthelefs, that fomewhat more than thefe Incidents ought to be re- 

 quired to eftablifli the charge of deception againft Savery, who, in the courfe of probabilities, 

 might have invented the fteam-engine half a century after the Marquis of Worccfter, whofe 

 defcription, clear as it now fecms to us who know the engine, was not perhaps enough fo as 

 to attract much attention, in company with one hundred other enigmatical propofals. Captain 

 Savery being a patentee, and having probably a confiderable intereft depending, might be as 

 ftrongly urged to fupprefs the Marquis of Worcefter's book on that account, as for the rea- 

 fonaficrted by Defaguliers. Aud with regard to the experiment of the flaik, it is- hardly 



allowable 



