Motion of a Current and the Prejfure of the Air, «97 



was fometlmcs dimJnifhed, by introducing a folid body into its upper part, to make it fill 

 fooner. Weight, rather above fix ounces. Length of lever, one foot ; it had holes in its 

 under edge to hang the veflel and weight at diflFerent diftances from its centre. The rife 

 of the water above the furface of water in the refervoir was one foot. I adopted this 

 height for convenience. There was no valve to prevent the column from defcending every 

 time the lower valve was opened. 



This particular defcription may appear tedious, but it will fave fome time and con- 

 fideration in the repetition of fuch an experiment. 



I entertain no doubt rcfpefting the operation of an engine of this kind, and that 

 a column of water may be raifed to any height, not much exceeding thirty feet, by pro- 

 portionally encreafing the preflure of water in the refervoir, and the dimenfions of the 

 conical tube : in many fituations, however, the requifitc quantity for this purpofe cannot 

 be had, others may not admit of fulEcient defcent, and in fome a refervoir fo deep may be 

 dangerous and inconvenient. 



Where the ftream has fuSlcient defcent, the water may be raifed by a number of liftt 

 inftead of one. 



Suppofe I, 3, 5, fig. 3. to be three refervoirs with conical tubes, and 2, 4, 6, three 

 cifterns, through which the raifed water is carried in fucceffion by a ftream paffing through 

 the three refervoirs, and afting upon three engines in the following manner: 



The cifterns 2 and 4 being filled with water, the current through the refervoir i will 

 raife a quantity of water into its engine, which will be emptied into the ciftern 2, at the 

 fame time the refervoir 3 raifes an equal quantity out of 2 into 4, and 5 another out of 4 

 into 6. 



The fame method may be ufed when there is plenty of water, but not convenience 

 for a deep refervoir; in this cafe the conical tubes may be fixed to different parts 

 of the refervoir, and all upon the fame level. Each engine muft be provided with a 

 lever and weight, to work its own valves ; but they may be all opened at the fame time 

 by the defcent of one veffel connefted to all the levers, or each by a vcffel conne£led 

 to that only. 



To quicken the reciprocations of the engine, and encreafe the quantity of raifed water, 

 a valve may be made to fupport the column of water in the afcending tube ; if the column 

 be not heavy, this valve may be contained in a cheft at the bottom of the tube : it will be 

 eafy to repair in this place ; a piece containing it may be fixed on with fcrews : it will 

 rife by the preffure of the water below. 



This kind of machinery, by altering the pofition of the rarefying tubes, will raife water 

 from a depth below the ftream equally as well as to an height above it j and in fituations 

 where there is plenty of water and convenience for a refervoir, a lower body of water 

 may be conveyed into a ftream above by the help of a fingle tube only ; one end of it 

 being placed in the water to be raifed, the other muft be introduced into the fmaller 



Vol. IV. — October i8co. Q^q aperture 



