Jo Hydraulic Machine at Schemnitz. 



. Each alternation employs about three minutes, and ralfes between twenty-nine and thirty 

 cubic feet of water, which, in the courfe of the natural day, amounts to twelve or thirteen 

 thoufand cubic feet of water, raifed by the fall of about double the quantity through a 

 foniewhat greater height. Two men * are required to attend it ; but M. Jars feems to 

 think, that on account of the Cmplicity and cheapnefs of its conftru£tion, and the little wear 

 and tear, together with the facility with which it may be made to work and flop for very 

 Ihort periods of time, it would be of great value in fuch places as afford the requifite fall of 

 fuperlor water, and do not require a higher fingle lift than fifteen or twenty toifes (or 

 fathoms.) 



The fall of twenty-two toifes given to the fuperlor water is not neceffary for raifing 

 the column of fixteen, though it is profitable, by Increafing the velocity of afcent. But it 

 was at firll intended to force the lower water as high as twenty-one toifes, which could not 

 be performed with the apparatus then fet up. For at the very firft introduftion of water 

 into the veffel D^ it burft with an effeft which fufficiently (hewed the power of fuch a 

 column of water comprefllng a mafs of air which, by its elafticity,_ was difpofed to give a 

 a vibratory or jerking motion to the agent. 



When the machine is near the end of its aftion, that is to fay, when nearly the whole of 

 the water has been raifed out of the refervoir I, if the cock M be opened to give vent to the 

 comprefled air, and a hat, or miner's bonnet, be prefented to the aperture P, the aqueous 

 vapours difperfed through the compreffed air, and perhaps alfo, fays M. J. part of thofe 

 of the external air, are condenfed on the bonnet, in the form of very white and compa£l ice, 

 very much refembling hall, and not eafily feparated from the bonnet : it foon melts, whichr 

 is not to be wondered at, as the temperature of the place itfelf is not cold. Meffrs. du 

 Hamel and Jars remained in Hungary from January to July, 1758, and obferved the fame 

 phenomenon at all feafons ; but as they had not a thermometer, they could not make a 

 number of experiments, which might have been of value in the inveftigation of the 

 fubje<fl. 



It is obfervable, that the air iffues out with fuch impetuofity, that the workman could not 

 hold the bonnet at the diftance of a few inches from the aperture, as he does in this ex- 

 periment, if he were not fupported behind. The ice is much more compaft if the cock be- 

 only in part opened. 



On the above, which is tranflatcd from the Memoir of M. Jars, with very little abridge- 

 ment, I have fcarcely any additional remark to make. The utility of this engine, under the 

 circumftances here ftated, is fufficiently clear, and its applications might become more ex- 

 tenfive, if the improvements fuggefted in the preceding note were added. In particular^ 

 where a ftream flows with the poffibility or carrying off part of the water by a deep 



• It fecms very eafy to conned the levers of the cocks above and below, to as to require only one man to 

 work the whole fet : and, indeed, there would be little difficulty in making the machine work itfelf fafely 

 without any attendant except to fet it off at firft, or flop it when requifite.— N, 



fliaft 



