All closets which depend upon a double trap violate rules 1, 4, 7, 11, and 13. Should anything get lodged in the lower trap, it is generally impossible to get it out without taking the entire apparatus down; and when the lower trap is formed in a single piece of earthenware with the rest of the closet, an obstruction therein could not, in some cases, be removed without breaking the closet open.
The side-outlet, or so-called wash-out type of closets, have a shallow bowl flushed by a strong stream of water, which is intended to drive the waste matters out of the bowl into a shallow trap underneath; they violate rules 1, 2, 3, 4, 7, 11, 12, and 13.
The flushing is usually attended with spattering. The standing water in the bowl is not sufficiently deep, and the manner of flushing is noisy and ineffective, the lighter wastes frequently whirling round and round for some time before being driven out. The trap is inconvenient of access, and its seal is very shallow, and easily broken by siphonage, evaporation, or incorrect setting, and being out of sight, the evil may not be discovered until the damage is done. The pipe surface between the basin and the pipe is easily fouled and difficult to clean.
In the effort to obtain a water-closet which should fulfill all of the above-mentioned requirements, the writer made use of a principle of hydraulics new in the practice of plumbing, namely, that of supporting a water column by atmospheric pressure acting only at its lower end. The principle is explained by the simple laboratory experiment of the inverted bottle in the basin of water (Fig. 415). If an ordinary bottle be filled with water and inverted in such a manner that its mouth shall be immersed below the surface of water in a basin below, the water in the bottle will be supported by atmospheric pressure acting on the surface of that in the basin. Let now this surface be lowered by any cause, and we shall find that it will be instantly restored from the bottle as soon as it sinks below its mouth, as shown in Fig. 416.
Fig. 415. Inverted Bottle.
Fig. 416. Water Exhausted from the Bowl.
This principle was applied to water-closet construction in the manner illustrated in Fig. 417. The water-closet represents our basin, and its supply pipe our inverted bottle, which is closed at its top by the cistern-valve. If water is exhausted from the closet bowl by evaporation, siphonage, or any other cause, a fresh supply descends automatically from the pipe as soon as the surface sinks below its mouth. Inasmuch as in the construction of the closet, this mouth is placed above the bottom of the water-seal, it is evident that water will instantly descend from the pipe before the seal can be broken. This seal is quite deep, and the mouth of the pipe is midway between the top and bottom of the seal that is below the normal level of the standing water in the bowl.
Fig. 417. Diagram illustrating the principle of the apparatus.
Fig. 418. Plan of closet.
Fig. 422 represents the actual construction of the closet.
The action of the apparatus is as follows: -
The cistern-valve being raised, the balance of atmospheric pressure is restored, the water column in the pipe instantly begins to move, and, since it connects with the water in the closet below its level, it acts noiselessly and effects a thorough flushing.
A novelty in the general principle of construction involves corresponding novelties in many details.
The lower end of the supply-pipe is not simply opened at a single point below the water level, but is conducted to two places independent of each other, the first being intermediate between the overflow of the trap and the bottom of the seal, as is shown in Fig. 417, and the second at the bottom of the trap. The first forms the mouth proper of the "inverted bottle" and supplies water to the flushing rim, and the second furnishes a jet which lifts part of the water out of the trap and bowl by its propelling power. Since both jets enter below the level of a large body of standing water in the bowl, their noise is deadened, and, as the supply pipe always stands full, they act instantly, and the flushing of the closet is very rapid. The lower jet causes the water and waste matters in the closet to sink into the neck of the bowl. Meanwhile the upper jet fills the passages and annular chamber leading to and surrounding the flushing rim, overflows, and, descending into the neck of the bowl, falls upon and drives out the waste matters collected in the neck quietly and without waste of water.
The cistern-valve being again closed, movement in the supply-valve immediately ceases, and the water in the flushing rim and passages leading thereto, falls back into the closet and restores the normal level of the standing water in the bowl and trap.
The form of the closet bowl is shown in plan in Fig. 418. The standing water has the shape best calculated to receive and deodorize the waste matters falling into it. It is deepest at the back of the closet, and very deep at the point where the wastes strike. Its surface is long and comparatively narrow, and is not round or elliptical, as has heretofore been customary.
Two of the writer's Experimental Closets.