means of a bend-no trap of any kind being placed at the foot of it; but where this is not the case, or where it is not proposed to ventilate the house sewer by means of the soil pipe, or where the soil pipe cannot be carried above the roof, it is advisable to place a disconnecting trap of some kind at the foot of the soil pipe outside the house. In any case it is necessary that provision should be made for a free passage of air through the soil pipe. Where the vertical soil pipe is at some distance from one or more closets, so that the branch pipes from the closets to the soil pipe are, perhaps, a few feet long, it is a good plan, and sometimes. necessary, to carry small ventilating pipes from below the traps of the closet, and connect them to a pipe outside the house, which should be continued up above the roof. This will prevent an accumulation of foul air in the branch pipes, and will also prevent the water passing down the main soil pipe from drawing the water out of the traps of closets beneath. It has even been proposed by Mr. Norman

Shaw to disconnect the branches of the soil pipes of the closets from the main soil pipe outside the house, by making them discharge into open heads, something like the heads of the rain water pipes; and Dr. Heron has devised a plan in which part of the branch pipe is movable, and so arranged that it is only connected with the main soil pipe when the lid of the closet is open, but is removed from it by the closing of the lid; while Mr. Buchan has proposed that the branch pipe should be a channel pipe, freely open to the air along the top.

Water closets should, whenever it is possible, be separated from the house by a ventilated lobby, or, at any rate, there should be two doors with special means of ventilation for the space between them, and this leads me to speak of Mr. Saxon Snell's invention, of which I have a full-sized model here, lent by Mr. Howard, the maker. In this, by means of an arrangement called "The Duplex Lid," the closet apparatus is placed, by the closing of the lid, in a shaft which is

carried up above the roof of the house. The water supply apparatus is also connected with the lid, so that the lid has to be closed in order to flush the closet. We come now to sinks and baths.

Of sinks there are various kinds. Sometimes sinks called "slop sinks" are provided to get rid of the dirty water, although where wash-out or hopper closets are used the slops may be thrown down them. The waste pipes from slop sinks should be provided with siphon traps, and are, as a rule, connected with the soil pipes. They are, in fact, looked upon in much the same light as water closets. The other upstairs sinks, as "housemaid's sinks," and the small sinks under taps, known as draw-off sinks, must not be connected with the soil pipe or water closet apparatus. Their waste pipes should always be provided with siphon traps immediately under the sinks, in order to prevent air coming into the house through these pipes, as it is rendered foul by so doing, but at the other end these waste pipes should always be

disconnected from the house sewer by discharging into a pipe with an open head like a rain water pipe, or over a gully in the area. Scullery sinks should also be disconnected from the sewer, but there is a difference of opinion as to whether or not this should be by means of a trap large enough to collect the fat from the greasy water thrown down there. If such a trap is used, it must contain a sufficient amount of cold water to cool at once the hot water from the sink that is thrown into it. But, in any case, the pipe from the sink should pass under an open grating before entering, such trap. The waste pipes from baths should also be invariably disconnected from the house sewer in the same way as those from sinks. The waste pipes of baths should be large, say two inches in diameter, not only so that they may be quickly emptied, but that the large body of water being discharged suddenly may be made to flush the house sewer. large houses where there are laundries, this is a still more important matter. A

In

bath should have a lead "safe" tray placed under it, the waste pipe of which must go straight through the wall of the house, and end in the open air. The disconnecting traps used in the areas for the waste pipes of sinks and baths may be either the ordinary siphon gully trap with a galvanized iron grating (the waste pipes being made to discharge either over the grating, or preferably, as a rule, through holes in the sides of the trap below the grating, but above the water in the siphon), or Mansergh's trap may be used, especially for scullery sinks or sinks on the basement floor.

To conclude. The principles that guide us in carrying out sanitary works are simple enough, but sufficient has been said in these lectures to convince every one that it is only by the minutest attention to details that we can hope to guard ourselves against the dangers that surround us, especially in the contrivances for the removal of refuse matters.