To recharge the generator, take the frame and the old cartridge from the case, throw away the old case and replace with a fresh one, proceeding as before. See that fresh water is put in the generator each time a new cartridge is used. [Illustration: FIG. 7.] In the tube through which the service pipe passes is a felt filter for taking the dust out of the gas. If the filter clogs, unscrew the cap to which the service pipe is attached, clean the felt, or replace it with a new filter, binding it in place by a stout thread or string. If the burner of the lamp does not produce a perfectly flat flame it has become clogged and should be cleaned with the burner cleaner furnished, or a new burner should be substituted, care being taken to put a little white lead on the nipple, if practicable, so as to insure a tight joint. In repacking the outfit in the case, throw out the water and wipe the can and generator parts dry. You can not be too careful to keep the apparatus clean. This is especially true of the small pipe that passes up through the bottom of the cartridge, with a cap over it. The cap should always be screwed in place, as its object is to prevent the water from squirting to the top of the cartridge. [Illustration: FIG. 8.] [Illustration: FIG. 9.] The back of the lamp can be removed by turning the small thumbscrew on the top and drawing out the pin which holds the shell into which is fitted the lens. It is not necessary to take the back out except to replace a lens, as the latter can be cleaned by opening the front door. If it is desirable to use the lamp as a hand lantern the flame can be turned on full by turning the button in a vertical position; this locks the key open. In the new model depress the key and lock it with the latch above the key. One charge of calcium carbide will supply gas to burn about one hour with the light turned on full, or for approximately three hours' signaling. [Illustration: FIG. 10.] If signaling is to be suspended for some hours, empty the water out of the generator and close valve _R_. The glass front can be replaced by taking out the wire spring. The glass cuts should be mounted in a horizontal position and, to prevent breaking, should be protected from rain when the lamp is hot. If a glass should be broken and an extra one is not available to replace it, signaling can be continued by turning the flame on full and using the heliograph shutter, a cap or piece of board in front of the lantern to obscure and reveal the flash. Without the protection of the cover the flame is easily blown out when turned low, but will not be extinguished even in a strong wind if the gas is turned full on. Old model lamps are serially numbered from 1 to 200, inclusive; the new model lamps are serially numbered from 201 upward.