=Lamps and Lanterns.=--Lamps and lanterns are commonly employed by engineers for making surveys inside the tunnel, and to light the instrument. For ranging in the center line, a convenient form of lamp consists of an oil light inclosed in glass chimney covered with sheet metal, except for a slit at the front and back through which the light shines, and on which the observer sights his instrument. To direct the operations of his rodmen the engineer usually employs a lantern, either with white or colored glass, much like the ordinary railway trainman’s lantern, which he swings according to some prearranged code of signals. Lamps and lanterns are used by the workmen both for signaling and for lighting the workings. For signaling purposes red lanterns are usually placed to denote the presence of unexploded blasts or other points of possible danger; and colored or white lights are usually placed on the front and rear of spoil and material trains. For lighting purposes, two forms of lamps are employed, which may be somewhat crudely designated as lamps for individual use and lamps for general lighting. Individual lamps are usually of small size, and burn oil; they may be carried in front of the miner’s helmet, or be fixed to standards, which can be set up close to the work being done by each man. Miners’ safety lamps should be employed where there is danger from gas. A great variety of lamps for mining and tunneling purposes are on the market, for descriptions of which the reader is referred to the catalogues of their manufacturers. Lamps for general lighting are always of larger size than lamps for individual use. A common form consists of a cylinder ten or twelve inches in diameter, provided with a hook or bail for suspension, and filled with benzine, gasolene, or other similar oil. Connected with this cylinder is a pipe of considerable length and small diameter through which the benzine or gasolene vapor runs, and burns when lighted with a brilliant flame. Lamps of this type burning gasolene were extensively employed in building the Croton Aqueduct tunnel. Various patented forms of lamps for burning coal-oil products are on the market, for descriptions of which the manufacturers’ catalogues may be consulted.