In dry methods of removing refuse, the “dust” is often added to the excreta, and the two removed together; or the “dust” may be separately removed. In either case the foul water, and to a large extent the urine, remain to be dealt with, and require special drains for their removal. Thus in large towns, whether dry or wet methods of removing sewage are adopted, drains for the removal of foul-water and rain-water will be required, and it is found that they are practically as foul as if they contained the solid excreta. The dry methods of removing sewage involve a certain amount of retention about the house; hence the general name of =conservancy methods=. Of these the most important are— 1. The pail system. 2. The dry-earth system. 3. The midden or privy system. =The Pail System= implies in reality the use of a movable cesspool. The pail may be used alone, or may contain ashes and house refuse, or some deodorant. Where the pail is used without any admixture of foreign matter, it should be emptied daily, and care should be taken that the pails for different houses are not exchanged. In the =Goux System= the tubs are lined with a composition containing clay and furnished at the lowest part with some absorbent material such as chaff, straw, or hay, which serves to absorb the urine and retard putrefaction. This is, when well managed, somewhat less offensive than the ordinary pail system. The pails may be supplied with a deodorant, such as sulphate of iron, as at Birmingham, Leeds, etc.; they may be packed with absorbent material, as in the Goux system (Halifax); the ashes and house-refuse may be deposited in the same pail (Edinburgh, Nottingham); or coal ashes may be scattered over the excreta (Manchester, Salford); but all these systems are rapidly being superseded. Although the pail or tub system is an improvement on the midden system, it is necessarily a cause of considerable nuisance, and its replacement by water-closets should be recommended in towns. In detached country houses it may be retained without nuisance, if the pail or tub is emptied daily, and its contents at once placed in the garden beneath a shallow layer of earth. The pails in large towns are usually collected in specially-constructed closed wagons. In some towns the pail contents have been burnt in a “Destructor” (page 200) after having been mixed with ashes. In other towns attempts have been made to utilise the excreta, either by selling in their crude condition or after drying and deodorising them by heat. None of these methods repays the cost of collection. Mixing ashes with the excreta diminishes any possible value they may possess as a manure.