The chief object of a perfect system of house drainage is the immediate and complete removal from the house of all foul and effete matter directly it is produced. The first object - viz., removal of foul matter, can be attained either by the water closet system, when carried out in this integrity; but it could, of course, be attained without drains if there was labor enough always available; and the earth closet or the pail system are modifications of immediate removal which are safe. Cesspools in a house do not fulfill this condition of immediate removal. They serve for the retention of excremental and other matters. In a porous soil it endangers the purity of the wells. The Indian cities afford numerous examples of subsoil pollution. The Delhi ulcer was traced to the pollution of the wells from the contaminated subsoil; and the soil in many cities and villages is loaded with niter and salt, the chemical results of animal and vegetable refuse left to decay for many generations, from the presence of which the well water is impure.

There are many factories of saltpeter in India whose supplies are derived from this source; and during the great French wars, when England blockaded all the seaports of Europe, the First Napoleon obtained saltpeter for gunpowder from the cesspits in Paris. Cesspools are inadmissible where complete removal can be effected. Cesspits may, however, be a necessity in some special cases, as, for instance, in detached houses or a small detached barrack. Where they cannot be avoided, the following conditions as to their use should be enforced:

1st. A cesspit should never be located under a dwelling. It should be placed outside, and as far removed from the immediate neighborhood of the dwelling as circumstances will allow. There should be a ventilated trap placed on the pipe leading from the watercloset to the cesspit. 2d. It should be formed of impervious material so as to permit of no leakage. 3d. It should be ventilated. 4th. No overflow should be permitted from it. 5th. When full it should be thoroughly emptied and cleaned out; for the matter left at the bottom of a cesspit is liable to be in a highly putrescible condition.

Where a cesspit is unavoidable, perhaps the best and least offensive system for emptying it is the pneumatic system. This is applicable to the water closet refuse alone. The pneumatic system acts as follows: A large air-tight cylinder on wheels, or, what answers equally, a series of air-tight barrels connected together by tubes about 3 in. diameter, placed on a cart, brought as near to the cesspit as is convenient; a tube of about the same diameter is led from them to the cesspit; the air is then exhausted in the barrels or cylinder either by means of an air pump or by means of steam injected into it, which, on condensation, forms a vacuum; and the contents of the cesspit are drawn through the tube by the atmospheric pressure into the cylinder or barrels. A plan which is practically an extension of this system has been introduced by Captain Liernur in Holland. He removes the faecal matter from water closets and the sedimentary production of kitchen sinks by pneumatic agency. He places large air-tight tanks in a suitable part of the town, to which he leads pipes from all houses. He creates a vacuum in the tanks, and thus sucks into one center the faecal matter from all the houses.

Various substitutes have been tried for the cesspit, which retain the principle of the hand removal of excreta. The first was the combination of the privy with an ashpit above the surface of the ground, the ashes and excreta being mixed together, and both being removed periodically. The next improvement was the provision of a movable receptacle. Of this type the simplest arrangement is a box placed under the seat, which is taken out, the contents emptied into the scavenger's cart, and the box replaced. The difficulty of cleansing the angles of the boxes led to the adoption of oval or round pails. The pail is placed under the seat, and removed at stated intervals, or when full, and replaced by a clean pail. In Marseilles and Nice a somewhat similar system is in use. They employ cylindrical metal vessels furnished with a lid which closes hermetically, each capable of holding 11 gallons. The household is furnished with three or four of these vessels, and when one is full the lid is closed hermetically, the vessel thus remaining in a harmless condition in the house till taken away by the authorities and replaced by a clean one. The contents are converted into manure.

In consequence of the offensiveness of the open pail, the next improvement was to throw in some form of deodorizing material daily. In the north of England the arrangement generally is that the ashes shall be passed through a shoot, on which they are sifted - the finer fall into the pail to deodorize it, the coarser pass into a box, whence they can be taken to be again burned - while a separate shoot is provided for kitchen refuse, which falls into another pail adjacent.

Probably the best known contrivance for deodorizing the excreta is the dry earth system as applied in the earth closet, in which advantage is taken of the deodorizing properties of earth. Dry earth is a good deodorizer; 1½ lb. of dry earth of good garden ground or clay will deodorize such excretion. A larger quantity is required of sand or gravel. If the earth after use is dried, it can be applied again, and it is stated that the deodorizing powers of earth are not destroyed until it has been used ten or twelve times. This system requires close attention, or the dry earth closet will get out of order; as compared with water closets, it is cheaper in first construction, and is not liable to injury by frost; and it has this advantage over any form of cesspit - that it necessitates the daily removal of refuse. The cost of the dry earth system per 1,000 persons may be assumed as follows: Cost of closet, say, £500; expense of ovens, carts, horses, etc., £250; total capital, £750, at 6 per cent. £37 10s. interest.