When it is required to construct a carbide-feed generator of large size or one belonging to the large carbide-feed pattern, it is preferable to arrange the store in a different manner. In N the carbide is held in a considerable number of small receptacles, two only of which are shown in the drawing, provided with detachable lids and hinged bottoms kept shut by suitable catches. At proper intervals of time those catches in succession are knocked on one side by a pin, and the contents of the vessel fall into the water. There are several methods available for operating the pins. The rising-holder bell may be made to actuate a train of wheels which terminate in a disc revolving horizontally on a vertical axis somewhere just below the catches; and this wheel may bear an eccentric pin which hits each catch as it rotates. Alternatively the carbide boxes may be made to revolve horizontally on a vertical axis by the movements of the bell communicated through a clutch; and thus each box in succession may arrive at a certain position where the catch is knocked aside by a fixed pin. The boxes, again, may revolve vertically on a horizontal axis somewhat like a water-wheel, each box having its bottom opened, or, by a different system of construction, being bodily upset, when it arrives at the bottom of its circular path. In no case, however, are the carbide receptacles carried by the bell, which is a totally distinct part of the apparatus; and therefore in comparison with M, the pressure given by the bell is much more uniform. Nevertheless, if the system of carbide boxes moves at all, it becomes easier to move by decrease in weight and consequent diminution in friction as the total charge is exhausted; and accordingly the bell has less work to do during the later stages of its operation. For this reason the plan actually shown at N is preferable, since the work done by the moving pin, _i.e._, by the descending bell, is always the same. P represents a carbide-feed effected by a spiral screw or conveyor, which, revolved periodically by a moving bell, draws carbide out of a hopper of any desired size and finally drops it into a shoot communicating with a generating chamber such as that shown in L. Here the work done by the bell is large, as the friction against the blades of the screw and the walls of the horizontal tube is heavy; but that amount of work must always be essentially identical. The carbide-feed may similarly be effected by means of some other type of conveyor instead of the spiral screw, such as an endless band, and the friction in these cases may be somewhat less than with the screw, but the work to be done by the bell will always remain large, whatever type of conveyor may be adopted. A further plan for securing a carbide-feed consists in employing some extraneous driving power to propel a charge of carbide out of a reservoir into the generator. Sometimes the propulsive effort is obtained from a