The mechanism for supplying the tenders of locomotive engines with water, necessarily differs according to its situation, the position of the source whence the water is derived, and other circumstances; but the arrangement usually consists of a cistern elevated about 10 or 12 feet above the railway, from which the water flows into what is termed a water crane, the head or neck of which turns on a pivot, and permits the water to be directly discharged by the opening of a valve or cock, into the reservoir of the tender. In the following cut, Fig. 1, is given an elevation of a water crane, with an improved valve applied thereto by Mr. Underhay, and for which he has taken out a patent. The external form of this portion of the water crane is shown at k; but in order that it may be better explained and understood we have shown this new "Cam-valve cock" (as the inventor terms it) in section, on a larger scale by Fig. 2. At a is the valve-box; b the inlet pipe; e the outlet pipe; f the valve, g the spindle which works through the stuffing box shown; h is the handle to the cam, which is cut away on both sides and through to the extent shown, and an arched piece s is left standing out from the centre (when viewed endwise), with an open space between it and the body of the cam.
The valve spindle has a cleft made in the upper end of it, the two cheeks of which carry a cross pin t. The arched piece s of the cam is inserted in this cleft behind the cross pin t, so that when the cam handle is brought down into the position shown, the cam acts upon the spindle and closes the valve with an intensity of force, insuring the contact of the opposite surfaces by merely the weight of the lever handle. To open the valve, it is of course only requisite to lift the handle. The simplicity of construction of this valve apparatus, and the ease and certainty of its operation, render it a very desirable appendage to railway water cranes.