£8 CONSTRUCTION OF AN HYDRAULIC APPARATUS. 



be very fmall, but the water pipe muft be wide enough to 

 empty the veflel in the fame fpace of lime that it was filled. 

 Each has a valve, but as they are all upon the fame level, only 

 the valves of the two water pipes are reprefented. All thefe 

 valves are clofed by Weights. Between thefe veflels is repre- 

 fented a wheel, with a weight fufpended on one fide, and the 

 veflel E on the other. Its rim has a groove, for the chains or 

 cords, and one fide is formed into teeth, to act upon another 

 toothed veflel above, which moves the cock in its axis. 



The veflel D receives water from the cittern C C, through 

 an aperture of a proper width, and is emptied by a fyphon as 

 often as the water riles to a certain height. 



The fyphon S S is about fix inches in diameter ; its Ihorter 

 branch riles thirty feet above the refervoir, and its longer 

 branch reaches five or fix feet below the furface of the water. 

 Its effcfts. Suppofe now that this inftrument is fet to work and fup- 



plied with a fufficient quantity of water. The cock in the air 

 pipe 1 above the veflel A mull be opened, and the vertical 

 pipes A C, and B C, muil be filled with water, by opening 

 a very narrow paflage between the air pipe and each of its 

 branches, while the valves of the veflels are clofed. 



This mode of proceeding is advifeable to prevent the fud- 

 den preflure of the atmofphere from forcing the air out of the 

 empty pipes, with fuch rapidity as would deftroy the operation 

 of the fyphon. After this, if all the valves are in good order^ 

 and all parts of the apparatus complete, no further attention 

 will be neceflary. 



The periphery of the lower wheel moves between the 

 valves of the veflel A on one fide, and thofe of B on the other, 

 and has a claw or pin to deprefs each in due order. The 

 weight fufpended upon the lower wheel opens the valves of 

 B, and by the afliftance of both wheels opens a communica- 

 tion between the air pipe 1, and the veflel A, whofe valves 

 have previoufly clofed their pipes. The preflure of the at- 

 mofphere accordingly fills A with water, and the air it con- 

 tained is carried down the ftream through the longer branch 

 of the fyphon. About this time the veflel D is filled to a level 

 with trie bend of its fyphon which conveys water in the veflel 

 E. This laft veflel being filled, overbalances the weight, and 

 moves the two wheels ; the valves of the veflel B are clofed 

 by their refpeclive weights, and the rarefying tube is made 



to 



