Following the types of water-closets mentioned above came the washout water-closet, which is in extensive use to-day, in some sections of the country. This fixture is shown in Fig. 130 and was a very great improvement over previous forms of water-closets. As compared with more recent types, however, the washout water-closet is seen to have certain serious defects. As seen in the illustration, this fixture has a flushing rim, a trap within itself, and a pool of water directly below the seal. The soil falling into this pool is removed by the force of the flush, the greater part of which is directed to this point. While there is no difficulty in removing the soil from the pool, in so doing the force of the flush, owing to the work of removing the soil, and to the construction of the fixture, is used up by the time it reaches the trap. Therefore the flush has not sufficient strength to remove the contents of the trap with force, the result being that the waste from this part of the • fixture is carried off more by overflow than by any other stronger force. In the washout water-closet the depth of water in the pool is not sufficient to submerge the soil, a point in which certain other water-closets are not lacking. Other defects in this form of fixture are that it has a large amount of fouling surface, and that it is noisy, the latter objection being due to the falling of the water from the pool into the trap.

The washdown water-closet, shown in Fig. 131, though appearing earlier than the washout, is superior to the latter in several ways. In the washdown closet the soil falls directly into the trap. Therefore the flush acts more directly and more strongly in removing waste from the fixture than in the washout, in which, as just observed, the soil must first be forced from the pool into the trap before being carried out of the trap. The washdown water-closet is provided with flushing rim and presents a smaller amount of fouling surface than the washout.

Although the washout and washdown fixtures were great improvements over other water-closets that had been brought out, it remained for the principle of siphonage to be applied to the action of the water-closet to make possible the high-class fixtures of the present day. The application of this principle has, indeed, resulted in a fixture of such perfect action and of such sanitary excellence that it is difficult to see how the fixture can be further improved.

In Fig. 132 is shown a sectional view of the siphon-washdown water-closet, the action of which is the following: The construction of the fixture provides a horizontal leg on the outlet of the fixture, which is somewhat contracted in area as compared with the vertical part of the outlet. When the waste of the fixture, in flushing, reaches the contracted horizontal leg, its passage is retarded to a considerable extent, which allows the entire outlet passage between the trap and the horizontal leg to completely fill with water. This solid plug of water, in passing off, creates a vacuum, and results in establishing the action of siphonage. This action is very strong, and quickly and forcibly pulls the entire contents of the trap out and into the drainage system. After the siphon breaks enough water enters the fixture to form the trap seal. Two or three flushes of the siphon water-closet may usually be obtained if desired, by allowing the supply to fill the flush tank to a higher level. After the first siphonic action breaks, the incoming flush quickly fills the outlet of the fixture a second time, and when the right conditions are reached, the fixture again siphons. The scouring action of this fixture, both within itself and on the connections into the drainage system, is far superior, it is clear to see, to that of any of the fixtures previously considered.

Fig. 132. - The Siphon Washdown Water-Closet.

Fig. 133. - The Siphon Water-Closet.

Another form of siphon water-closet is to be seen in Fig. 133. This type has two traps, one above the other. The second trap is not provided as a means of protection against the entrance of sewer air, but to aid in the formation of the siphon. As the flush enters the fixture from the flush tank, it divides, one half going through the flushing rim, scouring the bowl, and aiding in discharging the contents of the fixture. The other half of the flush passes through the passage shown in the illustration, directly into the lower trap. This jet forces the air between the two traps through the water of the lower trap, thus producing a partial vacuum, and forming a siphon, which rapidly draws out the contents of the fixture. This division of the flush not only siphons the fixture, but obviates the spattering which occurs in water-closets when the entire flush is thrown directly into the bowl, and at the same time, a more energetic passage of water through the lower trap is secured, which entirely prevents the possibility of anything remaining in the trap after the siphon has operated. Another good feature of this type of water-closet is that it is comparatively noiseless.

In addition to showing the features of this special type of fixture, Fig. 133 also shows apparatus for automatically starting the flush tank. The ordinary method is by means of the chain and pull, but in public toilet rooms, where it is often desirable not to depend on the individual using the fixture to flush it, the flush tank may be operated by the releasing of the water-closet seat. As will be seen from the illustration, this is accomplished by levers which operate a rod which in turn acts on the flush valve.