Fig. 65.—Syphonic closet.
"Of late years the principle of syphonic action has been applied to the washdown closet. Figure 65 shows the outline of a syphonic closet. It will be seen that the basin, as in the washdown closet, has considerable depth and holds a considerable quantity of water; but it differs in having a more contracted outlet. When the closet is flushed, the filling of this outlet forms a syphon, and then the pressure of the air upon the surface of the water in the basin drives the water into the soil-pipe with much force. At the breaking of the syphon, enough water is left in the trap to preserve the seal.
Fig. 66.—Syphon-jet closet.
"In the syphon-jet closet (Fig. 66) there is added to the mechanism of the syphon closet a jet of water which helps to drive the contents of the bowl more rapidly into the outlet. These two closets, syphon and the syphon-jet, are preferable to those of any other style. Among other advantages they are more nearly noiseless than any other kinds.
"Recapitulating, it may be said, while the short-hopper and the washout closets may not deserve absolute condemnation, the advantages of the washdown, syphon, and the syphon-jet closets are so much greater that they should be chosen in all new work."
Properly to flush out the closet, a water-pipe connection must be made from the supply main. It would be quite possible to connect directly to the closet rim where the flush enters, but there are two objections urged against this. Sometimes, when the pressure is low and water is being drawn in the kitchen, if a faucet in the bath-room is opened, not only will no water come, but air is drawn into the pipe by the force of the running water below. A direct connection with a water-closet, it is conceivable, might allow filth to be drawn up into the water-pipe under certain conditions. The other objection is that the small pipe generally used in a house does not deliver water fast enough for effective flushing.
It is common, therefore, to put in, just back of or above the closet, a small copper-lined wooden tank which holds about three gallons and which can be discharged rapidly through a one-and-a-quarter-inch pipe. This tank with fittings costs about $10, and in a great many cases is probably unnecessary. It has the advantage, however, of allowing a small flow to enter the tank whenever emptied, to be automatically shut off by a float valve when filled. If the house has a tank supply or if the pressure is strong enough to insure a positive flow at all times, there can be no objection in a single family, where the flushing action will be insisted on by the mistress of the house in the interests of cleanliness, to making a direct connection between the closet and the house supply pipe. An automatic shut-off bibb would then be used on the water-pipe, allowing the water to flow freely as long as the bibb was opened, but closing automatically when released.