The Viaduct Works' Handbook

99 small chain, attached to the piston already described, is put in motion by a common reciprocating lever, similar to a portable smith’s forge handle, or any other convenient means, and immediately the piston is moved it agitates the water and causes a partial vacuum in the wrought-iron cylinder, into which the water and sand are drawn through the projecting pipe, the water escaping through suitable valves arranged in the top in the manner shown by sketch, whilst the sand falls inside; a few strokes of the piston causes the machine to become filled with sand, when it is hoisted to the top, and a small suitable truck is ready to receive it; when in the truck the cottars are loosened, and the bottom of the machine is separated and another bottom is put on, and it is again lowered for a repetition. In some cases, where clay in small patches has to be encountered, the bottom of the machine is made with radial feathers of wiouglit- iron plate, + an inch thick, sharpened and steeled at edges; these are about 9 inches deep. When anything hard is met with the pump is lifted 3 or 4 feet and let fall again several times, and by this means the clay, or whatever it may be, is broken up, and can be easily drawn into the pump. The pump will lift stones, or even bricks if not too large for the projecting pipe; it has lifted many of 14 lbs. weight. The price varies according to the size of the pump, and is from £25 upwards. STRAINS ON GIRDERS. The method of ascertaining the amount of strain upon various parts of a girder, of class No. 1, is very simple. It may be