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WATER-PRESSURE REDUCER.

cylinder into the lower part of the globular valve, and so outinto the delivery pipe. When the latter is full, and the waterbegins to exert pressure, it presses upon the lower face of thepiston, giving it a tendency to rise. When the pressurereaches a point at whicli it can overcome the weights thathold down the piston, it forces up, and the rising piston carrieswith it the moving hollow cylinder which then (as it rises)closes the holes in the fixed cylinder, and thereby shuts off thewater in the supply from that in the delivery pipe. By tliisarrangement the pressure can be reduced to any requiredextent by varying the weights upon the valves.

Another form of valve to effect the same purpose is Barton& West’s Water-Pressure Keducer. In this valve, water from.a supply pipe passes into a chamber in which is a verticalpiston rod with a piston head at top and bottom. The wateracting on the under surface of the top piston, and on theupper surface of the bottom piston, balances the two, so thatthe flow of water lias no tendency to raise or lower the rod,which passes upwards through the top of the valve chamber,and is acted upon by a weighted lever which tends to press itdownwards. In so doing, it opens a circular aperture againstwhich the lower piston closes when the valve is sliut. Whenthe valve is opened it allows water to pass through the apertureinto a lower chamber, from which it flows into an outlet pipe.In the lower chamber the water presses against the lowersurface of the bottom piston (or rather upon a portion of itssurface, which is reduced in area by a cylindrical Prolonga-tion of its central portion) tending to force it up against theaperture. As long as this water-pressure in the lower chamberis less than that which acts upon the piston from the weightedlever, the piston will be held down. Water will then passfrom the supply pipe through this aperture into the lowerchamber, and thence into the outlet pipe. As soon, however,as the pressure in the lower chamber exceeds that transmittedby this lever, the piston will be forced upwards, and will close