PLOW 277 PLUMBING and lower parts white, the quills black. The summer plumage of the upper parts deep black, the front and sides of the neck pure white, with great black and yellow spots. Lower parts mostly deep black. _ Length about 10 inches. Its nest, in a depression of the ground, is made of a few dry fibers and stems of grass; the eggs, which are highly es- teemed as delicacies, are four in number, cream yellow or oil-green, with large GOLDEN PLOVER blotches of umber-brown. Plovers are gregarious in habit, and have a wide geographical range. The gray plover is Squatarola cinerea. PLOW, an implement for making a furrow in land, the object being to stir the soil, make a bed for seed, cover seed, hill up earth to crops, lay out lines for planting trees or shrubs, and for other purposes, according to construction. It may be drawn either by animal, steam, or gasoline power. Plows drawn by animal power, i. e., by horses or oxen, are divided into swing plows and wheel plows, the former being without wheels. The wheel plow has a forward carriage to regulate the depth of furrow, one wheel running on the land and the other in the furrow. Besides these there are also plows for special purposes; as, sub- soil plows, draining plows, etc. A bal- ance plow is one in which two sets of plow bodies and coulters are attached to an iron frame, moving on a fulcrum, one set at either extremity, and pointing different ways. By this arrangement the balance plow can be used without turning. _ In bookbinding, an implement for cut- ting and smoothing the edges of books. PLUM, the fruit of Primus domestica, the common plum, a sub-species of P. communis or that tree itself. It is a native of the Caucasus and Asia Minor, whence it was introduced into Europe at a very early period. It has run into more than 300 varieties. PLUMBING, the name applied to the system of pipes, valves, fittings and fix- tures installed in buildings which supply water and remove human excrement and liquid wastes. Heating systems and fuel piping are not in the strictest sense con- sidered plumbing. The earliest pipes were made of lead, but in modern practice this material has been to a large extent replaced by vitrified clay tile, cast or wrought iron, brass and copper. The exposed pipes in modern high grade buildings are nickel plated brass or white enameled metal. The water is usually brought to the property line by the water company, and connected with the house by a service pipe; the flow through is usually con- trolled by two valves, one for the water company, which may be located at the curb, and one for the building. Modern practice places a meter in the service pipe just inside the building. Usually there are two sets of pipes, one for hot water, the other for cold. The water is heated by a water front in a range, by a coil in the heating system of the house, or by a special copper coil which is heated by gas, the water usually goes from the heater to a riveted storage tank and is then circulated through the pipes to the various outlets. The end of each pipe from which water is to be drawn is fitted with a special type of valve called a faucet, and a good design demands that several valves be placed in the pipes in order that the water may be shut off from parts of the system without depriving the entire building from water. Fixtures. The materials used for fix- tures range from solid porcelain tx) iron. Solid porcelain fixtures are very expen- sive, liable to break in the handling nec- essary to installation and are very heavy. Metal fixtures upon which a heavy coating of porcelain has been fused are sanitary, resemble solid por- celain in appearance and are much more common and inexpensive. Marble has its vogue, but is seldom used now. Iron is used for heavy low grade sinks and soapstone for laundry tubs. The com- mon fixtures are sinks, used in kitchens and pantries, laundry tubs, wash bowls, bath tubs, water closets, shower baths and urinals. The modern water closet is of the siphon type in which the flow of water is controlled by a valve. The incoming water takes the place of water already in the bowl of the closet, which carries with it the wastes.
