_Disconnection Traps._--Whether the house drains into a sewer, a stream, a cesspool, or upon a piece of irrigation ground, one thing which must never be omitted is a disconnection trap or chamber between the house drain and the outfall. These traps--which should be placed close to the house--prevent any smell from the outfall passing into the house, and inasmuch as they have an inlet for the taking in of fresh air between the siphon and the house, this fresh air will course along the underground drains, and be discharged at the ventilating continuations of the soil pipes, or at the tops. [Illustration: 24. Disconnection Chamber. 25. Disconnection Chamber.] Where the house is so large that the air inlet of these siphons would not suffice, the latter are replaced by a chamber as shown in Fig. 24. The sewage flows into the air chamber formed by the half-open pipe _a_, being ventilated through the grating _b_; thence it passes through the siphon _c_ to the sewer in the direction of the arrow. There is a raking entry into the sewer side of the siphon at _d_, closed by a plug, thus preventing any smell from the sewer or drain beyond the siphon entering the air chamber _a_. If the sewers are at a great depth, the walls of the air chamber are made thicker, and a manhole is built the length of the open channel, an arch being turned over when the siphon is fixed, as in Fig. 25. The sewage passes from _a_ through the siphon _b_ to the drain _c_, _d_ being the air inlet. (Eassie.) [Illustration: 26. Houghton’s Trap.] One of the best modern traps is that introduced by Houghton (Fig. 26), in which the outlet _a_ at the bottom of the gully can be pointed in any direction, and the inlet _b_ to the basin _c_ of the gully, forming a movable half, can be turned round to accommodate the entering waste pipe _b_; _d_ is the open grating which covers the gully. _Drains._--Tho drain itself is got at by opening down to it in the front area. It may be found to be an old brick-drain, in which case it ought to be taken out. Brick drains are pervious, they allow the escape of foul air, and with contaminated air rats also get in the house. Wherever rats can get, foul air can go; and rats coming in through these holes may carry with them the poison of disease, such as typhoid fever. Rats generally go to the larder, and carry with them often the poison of such diseases, which are very largely spread by their poisons being taken in this way by rats into the milk and other foods, and also into the water in the cisterns.