i. e., that the pipe really passes into the sewer, the next thing to be done is to find out of what the house drain is made, or how it is laid. These points I have alluded to before, and shall therefore pass them over here. Next, make sure that the house drains are properly ventilated. The landlord or builder will probably tell you that they are trapped" and that no foul gas can pass the trap. This is a great delusion, and should not be listened to for a moment. The trap is a very useful and necessary thing, but it must not be expected to do more than it can, and in order to make this clear, I will explain what the common siphon trap is, viz., a bent pipe generally of the form shown in section in the sketch.

FIG. 7.

The common trap has not the ventilating pipe B.

These pipes always retain a certain quantity of water (indicated by shading in the figure) when in use, in the dip or bend. It will be observed that the upper part of the pipe dips into the water which completely fills the bend, and the water is sometimes said to "seal" the trap, and it is assumed that it will entirely prevent any gases from passing into the house. A little consideration. will show, however, that if the gas is generated in such quantities as to cause any considerable pressure in the sewers, it will readily pass through the water into the house. That this has actually happened, the following incident recorded by Dr. Carpenter will show. The ventilating pipe spoken of was in fact doing duty as a waterpipe from the cistern! "On the night of October 17th I was aroused by a loud noise proceeding from the closet; it continued at intervals throughout the next day. Unable at first to account for it, I eventually found that it was caused by the ventilating pipe doing duty as water-pipe to the overflowing cistern (during a very heavy rainfall). There was no room for

exit of foul air from the sewer, which, therefore, was forced through the trap of the water-closet, with, at times, the force of steam through the safety-valve of a steamengine. The nuisance continued for nearly three days before the weather would allow the plumber to rectify a mistake which had been committed in the previous summer, the mistake of making the ventilating-pipe do duty for a water-pipe." Dr. Carpenter then says that owing to there being no particular smell, this escape was tolerated, but in two or three days the occupants of the house were attacked by typhoid fever, and that in many other parts of the town enteric disease appeared at the same time.

The traps should be ventilated, and the ventilating pipe should not open into the house. I know no better means of ventilating the traps than that I have before described, and as shown in the figure above. In this A is the trap and B the ventilating pipe, the arrows indicate the direction of the flow of sewage from the house to the sewers. It will be obvious that if any accumulation of gas takes place

in the sewers, it will pass up the ventilating pipe B, instead of forcing the trap and flowing into the house. Therefore, insist on the drains being ventilated, or do not take the house.

There are several kinds of trap, but the principle of all is nearly the same.

Having settled these preliminaries, let us consider the house itself, and examine it carefully.

I need hardly say that this can scarcely be done satisfactorily by the intending tenant or purchaser, unless he has a far greater knowledge of building and sanitary matters than falls to the lot of most nonprofessional men, but much may be accomplished by the diligent use of eyes, and nose especially, if they are used in the right

way.

The foundations and basement may reasonably claim attention first. Under all the walls there should be a mass of good concrete, and the whole area on which the house stands should be covered with the same in a layer, not less than 6 in. thick. This layer of concrete, if made with good

hydraulic lime, or better still, Portland
cement, will not only prevent damp from
rising into the house, but will keep out
those domestic pests, rats, mice, and black-
beetles as well. In all damp soils con-
crete under all basement floors should be
insisted upon.
If it is not there, and
the landlord will not put it, do not take the
house.

Next, note the thickness of the walls. If any external brick wall is less than 14 in. thick, the house will always be damp and uncomfortable. Examine the water-closets, especially as to position. I have already entered into this question, and will not therefore say any more about it here. Look to the water cisterns, and find out where the waste pipes go to. If into the soil pipe of the water-closet, or into the drain, as is commonly the case, have them altered at once. Dr. Carpenter's experience will give a reason for this. Both rainwater pipes and waste-pipes from the cisterns should not run directly into the drain, but should have their ends visible outside the house, and above the ground.

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