_Method of gas generation._--The method employed for producing acetylene in the signal lantern is by bringing water into contact with calcium carbide. The disadvantage of this method is that when the water is not in excess and does not entirely surround and touch each piece of carbide the heat of generation will so change the chemical properties of the gas that combustion at the burners is not satisfactory. This change is technically known as "polymerization," or the breaking up of acetylene into other hydrocarbons, such as vapors of benzine, benzole, etc. These form a tarry substance which is apt to condense at the burner tip and clog the openings. Also they deposit carbon on the burners, as they require more air for perfect combustion than does pure acetylene. Another disadvantage of this system is that after the carbide and water are in contact, generation of gas will continue until all the water is absorbed. Where, however, portability of the generating apparatus is desired and resort to this method is necessary, the objections are not important, if the apparatus is well constructed and care is taken in its use. _Description._--This equipment consists of a signal lantern with cartridge generator attached. The lantern is equipped with a special aplanatic lens mirror, 5 inches in diameter and about 3 inches focus. The lantern is packed complete in a wooden case with shoulder straps and the following extra parts are included, each part having its own receptacle in the case: 2 burners; 1 cover glass; 3 cartridges of calcium carbide of 5 ounces each; 1 pair of gas pliers; 1 tube white lead; 1 extra filter bag; 1 screw-driver. [Illustration: FIG. 4.--The signal lantern.]