. Machinery and processes of the industrial arts, and apparatus of the exact sciences. ing screwsd and / of the pivots. When the piston is at the end of its course ineither direction, the cylinder will be truly vertical. In this position thepiston is momentarily at rest, and both induction and eduction valvesshould be closed. Accordingly the dispo-sition of the parts is such that, when thecylinder is vertical, the openings by whichthe channels j j communicate with thesupply and discharge pipes present them-selves exactly opposite to the solid sectordividing h from i. In the next momentthe flow
. Machinery and processes of the industrial arts, and apparatus of the exact sciences. ing screwsd and / of the pivots. When the piston is at the end of its course ineither direction, the cylinder will be truly vertical. In this position thepiston is momentarily at rest, and both induction and eduction valvesshould be closed. Accordingly the dispo-sition of the parts is such that, when thecylinder is vertical, the openings by whichthe channels j j communicate with thesupply and discharge pipes present them-selves exactly opposite to the solid sectordividing h from i. In the next momentthe flow of water will recommence, thecylinder discharging itself from the fullside of the piston, and filling anew on theopposite side. Fig. 31. From this statement it is apparent that the influx and efflux of thewater proceeds with more and more freedom from the beginning to themiddle of the stroke, when the passages are at their maximum opening,and that from this point to the end the reverse takes place. But it is tobe also observed that, from the nature of crank-motion, the velocity of. 108 PARIS UNIVERSAL EXPOSITION. the piston varies correspondingly, and that the relation of the supply ofwater to the demand is very nearly constant. Very nice adjustment is evidently necessary in these engines, in orderthat the moment of the absolute closing of the valves may correspond tothat of the completion of the stroke; and as it is possible that thisperfect coincidence may not be exactly secured or permanently main-tained, some provision against counter-pressure and the effects ofhydraulic shocks is necessary. Air chambers and relief valves areemployed for this purpose. The relief valves open a backward commu-nication between the cylinder and the driving column, so that if thereoccurs an obstruction to the discharge, the pressure on the two sidesof the piston will be equilibrated by the opening of the valve. The engines constructed by Messrs. Eamsbottom on this model aregenerally small, some
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