1160

THEORY AND PRACTICE OF ENGINEERING.

Book II.

bottom of its muzzle, the quantity of water elevated in a certain time is measured, takenas unity through the ascending tube G I H ; and by varying the distance from the valve Dto the orifice C, the water in the body of the ram receives the velocity which correspondsto the maximum effect of the machine.

In the second operation, the air contained in the space M N is compressed by the forcedeveloped in the first operation, which abo drives the water through the orifice E, in thereservoir of air F, and into the ascension pipe H, when the valve E immediately falls byits own weight from its muzzle into the orifice E, and the stopping plug I) again closesthe orifice C : the two valves being closed, the air compressed at m 11 reacts, and althoughthe time of this reaction is scarcely perceptible, the effects resulting from it have a greatinfluence on the play of the ram; the reaction obliging the water to return from the headof the ram towards the source, which forms a void at the extremity of the head; theatmosphere presses on the stopping valve D, the orifice C opens, and the water from thesource contained in the body of the ram A B C, in flowing through this orifice, reassumesits primitive velocity : the water continues to elevate itself in the ascension pipe GH, bythe elasticity of the air compressed in the reservoir F, which acts on the water and forcesit to rise. The motion of the ascending column of water communicates itself to the airof the reservoir F, which would soon be emptied if a fresh portion were not introducedinto it at each revolution of the ram: the little channel s, closed by a valve, conducts thisair; the valve opens from the exterior towards the interior of the ram, in consequence ofthe void formed by the fourth operation, and a certain volume of atmospheric air entersthe little cylinder abed, situate below the reservoir E, into which it is driven, a portionbeing arrested in the space win, and forming the elastic body we call a bed of air; it isthe reaction of this compressed air which causes the water contained in the body of theram to return to the source.

It results from this description of the hydraulic ram, that its principal parts are, 1st,the body of the ram; 2dly, the head which comprises the stopping-valve, the ascension-valve, the air-valve, the reservoir, and the bed of air; 3dly, the ascension-pipe. "We donot, as yet, know the dimensions which should be given to the different parts of the ram,in order to ensure the greatest effect possible from a source of water. An experimentwas made at Marly, which showed the application of the hydraulic ram on a large scale;the mean fall was 1*62 metres; this height is the mean difference between the levels aboveand below the Seine : the body of the ram which was constructed was 33 centimetres internaldiameter; the vertical height to which it ought to have elevated water is 155'5 metres:it is principally for these large rams that recourse must be had to experiment, and tomake a great number of observations on the form, dimensions, and general disposition ofthe parts which compose them.

As for the lesser rams, experience has brought them to a great degree of perfection, andthose who use them praise them highly. A mechanic who should compare the quan-tities of water expended to the quantity elevated would conclude that the ram wasthe best hydraulic machine; it has, above most others, the advantage of being applicable tothe least abundant sources of water; the least fillet of water can move a ram by giving itdimensions coincident with the moving power: with regard to economy there is no machinewhich requires less expense for its first establishment and maintenance.

To give a precise idea of the dimensions of rams which have been employed, we mustrefer to those which have been constructed, 1st, at Lyons, by Fay Sothonav, Mayor ofLyons; 2nd, at the bleaehing-ground of Turquet, near Senlis ; 3rd, at Clermont Cise,under the sub-prefecture of Larochefoucauld.'

The source of Fay Sothonav gives 84 litres per minute; the fall of this source is 10*6metres: by taking a cube diameter of water elevated 1 metre as the unit of force, thepower of the source during one minute will be expressed by 890. The body of the ramis 54 millimetres diameter, and the length 32 *5 metres. The ascension tube was 227 metreslong; it furnished 17 litres per minute. The water was elevated to a vertical height of34'1 metres ; thus the force transmitted by the ram during one minute is expressed by 579 ;

579

the relation of this number to the expenditure of power in one minute is —— =

o 90

65

100 *

The body of Turquet’s ram was cast-iron, 0203 metres in diameter, and the lengthabout 8 metres; it elevated water to a vertical height of 4'55 metres; the quantity soelevated in one minute was expressed by 1224; the source furnished in the same time 1987litres; its fall was 0'979 metres; its force in one minute was 1945. The relation of thetransmitted force to that expended was then =

Delca^san, who executed Turquet’s ram, lias verified by experiment the importance ofgiving to the tubes which form the body of the ram, as well as to the wood or stonesupports of the tubes, the greatest solidity; he conceived that the force employed tomove the body of the ram or its support is lost for the effect we wish to obtain. Havingremarked that, by increasing the head of the ram, the machine would elevate a greater