Cisterns are usually actuated by means of a chain and handle attached to the flushing lever. To prevent the swinging of the handle a rod may be substituted for the lower part of the chain, and made to pass through two brackets projecting from a back plate, as shown in fig. 121 A. For asylums a brass slide working in a dovetailed groove is sometimes used, the whole of the chain being enclosed in a casing, so that the inmates cannot tamper with it; this is a convenient arrangement, and has a good appearance. A more novel device is a press-button, like that used for electric bells, but this is only applicable to special kinds of cisterns. Automatic action is desirable in certain places. Numerous devices have been designed, including seat, treadle, and door action. One example of seat-action was illustrated in fig. 105, and another has been described under the heading of pneumatic cisterns. The mechanism ought to be as simple as possible.

Flush-Pipes

Flush-pipes from cisterns fixed in the usual manner about 6 ft. or 7 ft. above the floor are commonly 1 1/4 in. or 1 1/2 in. in diameter according to the type of cistern, and may be of lead (not less than 9 lbs. per yard for 1 1/4-in. pipe and 10 1/2 lbs. for 1 1/2-in.), or of galvanised iron, copper, or brass. Flush-pipes of the three last-named metals, bent to the proper curves, are supplied by the makers of the cisterns and closets, and are more easily fixed than lead pipes; they have also the advantage of being of the length which has been found by experience to be best suited to the closet and cistern. Galvanised iron can only be recommended for cottages, workshops, and other places where strict economy as well as rough usage must be considered. The brass pipes may be either polished or nickel-plated, and the copper may be finished in the various ways already described. Unnecessary

Fig. 121 a.

Closet Pull with Rod and bends should be avoided, and all bends required ought to be as easy as possible so as not to reduce too much the velocity of the water. It is a good plan to fix a clip and indiarubber buffer on the flush-pipe at the proper height to receive the hinged flap or seat when these are raised.

Back-Plate.

The nozzle formed on the closet for receiving the flush-pipe is generally horizontal, but in some closets it is vertical, so that no bend is required at the foot of the flush-pipe.

Overflows

Overflow-pipes from flushing cisterns are almost invariably of lead 3/4 in. in diameter and weighing not less than 5 lbs. per yard. For high-pressure supplies, a larger overflow is desirable. The pipes ought to be carried through the nearest wall and left with the end open or merely covered with a flap. They ought not to be connected with the flush-pipes of siphon cisterns, even if there is no water company to object, as the connection will interfere with the siphonic action, at any rate if the joint is not close to the closet-basin.