This section is from the book "The Principles And Practice Of Modern House-Construction", by G. Lister Sutcliffe. Also available from Amazon: How Your House Works: A Visual Guide to Understanding & Maintaining Your Home.
Fig. 304 - Section of Basin's Direct-acting Valveless Waste-preventer.
The cisterns which have been referred to as discharging their whole contents automatically are, with one or two exceptions, constructed on the principle of syphon, and are therefore often known as "syphon cisterns". The pull of the handle brings into action mechanism of some form or other, which, by disturbing the baalance of air-pressure, starts the syphon and empties the cistern. One of the earliest and simplest of this kind of Hushing cistern is " Bean's Patent Direct-acting Valveless Waste-preventer". A section of this apparatus is given in Fig. 304, and will serve as a type of many others of varying excellence. The syphon is started by pull-ing the handle or chain attached to the lever, one end of which is fastened to the dome or short leg of the syphon. The dome being lowered, water flows over the lip of the long leg of the syphon, the pressure of air above the water inclosed between the long and short legs is reduced, and the syphonic action is started. There are numberless devices for attaining the same end, some of them more complicated than others; but it is scarcely necessary or profitable to describe their many variations of detail.
A flashing cistern that answers well in practice, and contains neither valve nor syphon, is one in which the water is discharged by the tipping of a receptacle hang in the cistern on pivots. This also may be classed with the automatic type of cistern.
Reference must be made to flushing cisterns provided with valves. They are not to be recommended for general use, inasmuch as the valve is closed, and the flow of water ceases immediately the handle is released. They are useful for supplying valve-closets, because the after-charge can be arranged with ease and simplicity.
One great objection, that is commonly and with much reason urged against all classes of flushing cisterns, is the noise that seems inseparable from the use of even the best. Noise to some extent is inevitable when a large body of water is discharged quickly; but anything that reduces or minimizes the avoidable noise, i.e., that which results from the mechanism of the apparatus, is a distinct gain. The noise of the water entering the cistern may be greatly reduced by carrying the inlet pipe to the bottom of the cistern, as in Merrill's "Noiseless" cistern, and a new cistern has recently been brought out, known as the "Water-witch", in which the same end appears to have been gained.
Portable water-closets with cisterns at the side an simply an improvement on the ordinary commode, and belong really more to furniture than to sanitary fittings. The water is forced into the basin by a small hand-pump, worked by a handle fixed in the ordinary way at the side of the basin.
The question of automatic flushing by a mechanical apparatus, connected either with the seat or the door of the closet, has l>een frequently attacked, but it cannot be said to have been successfully grasped. By an arrangement of levers attached to the seat, the water is admitted to the basin cither before or after use, the weight of the user setting the machinery in motion. Another plan is to connect the outlet-valve of the Hushing cistern by a rod and crank with the door of the closet, so that each time the door is opened the basin is Hushed. In either case the mechanism involved is of such a nature that it is very easily put out of order, and when that is the case, the closet is worse than useless. The object aimed at is a mast excellent one; and any one who invents a really efficient and lasting automatic apparatus will confer a great boon on the community.