Fig. 18.—Jennings closet.
4. It is evident that if the hopper-closet could have its trap bent to one side out of sight, and its hopper enlarged toward the bottom, so that nothing would strike and cling to its sides, it would be an excellent one. Of such a type are the Tidal-Wave and National closets (Fig. 19), a being the water-pipe, which discharges into a flushing rim, and b a vent-pipe to relieve pressure between the two bodies of water during a discharge, and prevent siphoning.
Fig. 19.—Tidal-wave closet. Fig. 20.—Y-branch. Fig. 21.—Quarter bend.
A water-closet, to be well flushed, should have a discharge of three gallons of water in five seconds, sent directly downward all around the rim.
School-sink (also called trough-sink or privy-sink). An iron trough, having a sewer-connected opening with a movable iron plug in the bottom at one end, for the discharge of its contents, and a pipe at the other end, from which it is filled with water. It is practically an elongated water-closet. (See 53.)
12. Y-branch (Fig. 20), so named from its shape. There are also half Y-branches.
Eighth bends. There are also quarter bends (Fig. 21), sixth bends, and sixteenth bends. These are used in pipe-connections in order to discharge the contents of the branch pipes in the same general direction with the current in the main pipes, for, if the discharge enters at a right angle, a deposit is apt to form opposite the point of connection.
14. Trap in house-drain. Intended to cut off all communication between the house and the street sewer. If a contagious disease occurs in one’s own house, he can be sure that the excreta are disinfected, and that disease-germs can not escape into the air, even if the pipes happen to be defective; but he can not be sure that such excreta are properly disinfected in other houses. The only safe way, therefore, is for each house to be cut off from all others by the means described. The objections to the trap on the house-drain are, that it forms a slight obstruction to the flow of drainage, and is liable to be obstructed by deposits, and that it favors “cushioning,” i. e., the forcing of smaller traps, when the air in the drain is compressed between this trap and a down-coming mass of water. (See “Bad Odors,” 1, d.) The first of these objections is met by making the trap a half S one, so that the fluids fall down one limb with sufficient force to wash out the bottom of the trap thoroughly with each discharge, and the second by the fresh-air inlet, which relieves the pressure that otherwise might force the traps.