HYDRODYNAMICS. 



567 



CCCXXIV. 

 ,9. 



Hydraulic valve D is exactly the same as C, only it descends as in 

 ^ *" the figure when it shuts, and rises when it opens. 



The upper part of the head of the ram at E is made 

 flat, and has several valves which allow the water to 

 pass freely from the pipe AB, but prevent its return. 

 On each side of the head of the ram, at the part opposite 

 to these valves is a hollow enlargement, shewn by the 

 r,nt dotted lines K, forming a circular bason, through the 

 centre of which the pipe ABR passes. This part of the 

 construction is shewn more distinctly in Fig. 9. which 

 is transverse section through LEZ in a plane perpen- 

 dicular to that of the paper. The pipe is here made 

 flat instead of circular, as seen at E, Fig. p. for forming 

 the seats of the valve*, anil the bason K K is covered 

 with an air vessel FF. This air vessel communicates 

 all round the pipe B, with the bason KK, and with 

 the vertical pipe Si. 



The machine being thus constructed, let us suppose 

 the pipe ABR full of water, and the valve C to be open- 

 ed, the water will lift the valve D, and escape with a ve- 

 locity due to the height of the reservoir. In a short 

 time, the water having acquired an additional velocity, 

 raises the valve G, which shuts the passage, and pre- 

 vents the escape of the water. The consequence of 

 this is, that all the included water exerts suddenly a 

 hydrostatic*) pressure on every part of the pipe, com- 

 pressing at the same time the air in the annular space 

 i, which by its elasticity diminishes the violence of 

 the shock. This hydrostatical pressure opens the valves 

 at E, and a portion of the water flows into the air vessel 

 F, and condenses the air which it contain*. The valves 

 at E now close, preventing the return of the wjter into 

 the pipe, and the water recoils a little in the tube with 

 a slight motion from B to A, in consequence of the reac- 

 tion or elasticity of the compressed air in i i, and also 

 of the metal of the pipe, which most have yielded a 

 little to the force exerted upon it in every direction. 

 The recoil of the water towards A produce* a slight as- 

 piration within the bead R of the ram, which causes the 

 valve D to descend by its own weight, and prevent the 

 water X which covers it from descending into the tube. 

 The air, however, passes through the pipe / It, opens 

 the valve It, and a small quantity is tucked into the 

 annular space i i ; but the quantity is very small, as the 

 valve k closes as soon as the current of air become* ra- 

 pid. During the recoil towards A, the valve C, being 

 unsupported, falls by its own weight; and when the 

 force of recoil is expended by acting on the water in 

 the reservoir PQ, the water begins again to flow along 

 ABR, and the very same operation which we have de- 

 scribed is repeated without end, a portion of water be- 

 ing driven into the air vessel F at every ascent of the 

 valve C. The air in this vessel being thus highly com- 

 pressed, will exert a force due to its elasticity upon the 

 surface of the water in the vessel F, and will force it 

 up through the pipe M to a height which is sufficient to 

 [mm tii.- i ' 



Hydraulic 

 Rain. 



elasticity of the included air. 



The small quantity of air which is drawn into the 

 annular space i 1 through the air tube /* at each aspi- 

 ration, caose* an accumulation of air in the space i i ; 

 and when the aspiration of recoil takes place, a mull 

 quantity of air passes from i i, and proceeds along the 

 pipe till it arrives beneath the valves at E, and l< 

 in the small space beneath the valves, it is forced into 

 the air vessel at the next stroke, and thus affords a con- 

 stant supply of air to the vessel The valves m-iki in 

 fWlial from 50 to 70 nutation* in a minute. 



n the fall of water or PQ, is five feet, and the 

 pipe AB six inches in diameter and 1 t feet long, a ma- 

 chine with its parts proportioned M in the figure will 



Form of the 

 ram for 

 raising 

 clean water 

 with fool 

 water. 

 Fig. 10. 



KOTTI of the 

 machine 

 for pixdu* 

 cing a cur- 

 rent of air. 

 Fig. II. 



raise water to the height of 100 feet. It will expend 

 about 70 cubic feet per minute in working it, and will 

 raise about 2y cubic feet per minute to the height of 

 100 feet Mr Millington observes, that one of these 

 machines is said to have raised 100 hogsheads of water 

 in 24 hours to the height of 1 34 feet by a fall of 4 1 feet. 



The form of the ram represented in Fig. 10. is suit- 

 ed to the case where a current of foul water AB, is em- 

 ployed to raise clean water from the well WW. This 

 effect is produced by a bent pipe OPQ, containing a 

 column of air from O to Q, and by another pipe T, 

 with a suction valve t : The mode of action is pre- 

 cisely the same as in Fig. 8. When the valve C shuts, 

 the sudden hydrostatical pressure forces the water up 

 the bent tube at O, compresses the column of air OQ, 

 which again presses, by its elasticity, on the surface of 

 water at Q, and forces the clean water up through 

 the valves into the air-vessel FF. The recoil of the 

 water from B to A will produce a rarefaction in the co- 

 lumn of air QO, in consequence of which, the atmo- 

 spherical pressure upon the water in the well will raise 

 trie valve t, till as much water is admitted as was driven 

 into the air-vessel. Montgolfier proposes to substitute 

 a straight pipe in place of OQ, and to place a piston, 

 moving freely in the pipe, which will transmit the 

 pressure from the foul water to the clean water, with- 

 out allowing them to mix. We conceive that the same 

 effect might be obtained more simply and with much 

 less friction, by a very loose diaphragm fixed in the tube. 



When the ram is employed to produce a current of 

 air, it has the form shewn in Fig. 1 1. The air is ex- 

 pelled through the air-pipe rr m, in consequence of the 

 mass of water rushing into the air-chamber W, by the 

 shutting of the valve C. The water in W is prevented 

 from following the air by a hollow ball of copper n, 

 which floats on the water, and shuts up the lower end 

 of the pipe, when the water dashes into W. When 

 things are in the state shewn in the figure, and all the 

 air expelled from the chamber W, the air compressed 

 in the annular space pp, (which serves the same pur- 

 pose as ii in Fig. K.) produce* a recoil of the water. 

 The valve D shuts, C opens, the water quits the cham- 

 ber W, and the valve if shuts, and prevents the admis- 

 sion of air. At the same time the valve r opens, and 

 admits a fresh supply of air into the chamber; but when 

 the water has descended below the float t, this float de- 

 scends, and by its rod ed shuts the air- valve d. When 

 the force of recoil is spent, the water flows again from 

 A to B, and the operation which we have described is 

 again repeated, so that there is constant current of 

 air in the pipe ic m, which may be equalised by a water 

 regulator, or any other contrivance. See the Repertory 

 of Art*, Dec. 1 8 16; Ferguson's L'duret, vol. ii. App. ; 

 and Brande's Journal, vol. i. p. 211, Lond. 1816. 



16. Deicriptto* of Ike Chemnitz Fountain, or Hungarian 

 Machine. 



The Chemnitz fountain is represented in Plate Chemnitz 

 CCCXXIV. Fig. 12. where C is a collection of water, fountain. 

 either in a mine or in a well, which it is required to raise Fig ' "' 

 to the reservoir B by means of a small head of water at A. 

 In order to effect this, a pipe AFT, 4 inches in diame- 

 ter, having a cock at M, enters the top of the copper 

 vessel TD, 8$ feet high, 5 feet in diameter, and 2 inch- 

 es thick, containing about 170 cubic feet, and extends 

 to D within 4 inches of the bottom. The vessel TD 

 has a cock at N, and a very large one at P, and from 

 its top proceeds a pipe TOG, 2 inches in diameter, 

 with a cock at O, entering the top of the vessel KE, 

 which is 6} feet high, 4 feet in diameter, 2 inches 



