i8 Hydraulic Machine al Schemnitz. 



*' forejgn fubftance mixed it. This faft is fo plain, that it has even ftruck M. Dolomieu^ 

 *' in the midft of his prepofleflions in favour of fomcftrange inconceivable power, which 

 " he attributes to volcanic fire, of melting earthy fubftances, without efFe£ling an alteration 

 " in their fenfible qualities. " I hope," fays he, " to prove, that lavas contain, in their 

 *' interior, a combuftible matter, which burns and confumes in the fame manner as other 

 " inflammables," IJles Ponces, lo. Yet he neglefts telling us what this matter is; though 

 " it plainly appears to, be no other than fulphur and bitumen, of which an immenfe quan- 

 " tity is found in all volcanos, which liquefies in a low degree of heat, and caufes all the 

 *• ftony fubftances to flow that are immerfed in it." 



(To be continued.) 



IV. 



On the Hydraulic Machine ereBed at the Mines of Schemnitz in Hungary. 

 To Mr. NICHOLSON. 



SIR 



T 



A HE early infertion of the cxtraft which I fent you from the Micrographia of Robert 

 Hooke in your laft Number, encourages me to requeft you will give fome account, with 

 your opinion, of a machine for raifing water at the mines in Hungary, upon the principle 

 of the fountain of Hiero. It is flightly mentioned in many elementary books, but I cannot 

 point out the work in which it was originally publifhed, nor fay thing more than that I 

 believe it has not been accurately defcribcd in any Englifh work. 



I am, Sec. 



R. B, 



London, Feb. 20, 1800. 



The account was firft given to the Royal Academy at Paris by their correfpondent, M, 

 Jars, and inferted in their Memoirs for the year 1768. The machine was executed in 

 the year 1755, and ufed to raife the water of a fhaft named Amalie, in the mines at Schem- 

 nitz. Fig. 1, Plate 2, is copied from the engraving of Jars. It is placed at the depth of 

 forty toifes beneath the furface of the ground above. The wooden trough A is a 

 kind of refervoir at the end of a channel which conveys the water by which the machine 

 is worked. The pipes are not drawn in the proportion of their lengths, but contrafted to 

 the fpace of the defign. B B conveys the water from it into the refervoir D, which is 

 twenty-two toifes lower than A. This pipe defcends very nearly to the bottom of D, as 

 js (hewn by the dotted line, with the intention that the included air fliall be forced to 



afcend 



