less a supply of cold water were immediately turned on to prevent it.

This method is very economical if properly constructed in the beginning, an ordinary water-closet hopper, with a provision for flushing, taking the place of the more expensive pan or plunger-closet.

Another method of ventilation and one more easily applied to old systems of wastes is shown by illustration No. 2.

The upright soil-pipe is taken out through the roof so as to prevent pressure from a collection of gas. The water-closets and other fixtures are all trapped, and each is separately ventilated by a tube, which must be taken to a heated flue. In this plan, the conductors for rain water may enter the drains or soil-pipes at any place. Some of the smaller wastes may have merely a gas-proof trap, the ventilating-pipe being omitted.

The private sewer should be trapped before it connects with that of the street, so as to prevent the flow of gas into the house pipes. It is not desirable to attempt to ventilate the public

sewer.

The ventilating-pipes from water-closets should start from beneath the seats, and the seats should be raised above the earthenware bowls to allow the flow of air over the edge of the bowls to the ventilating-pipe.

Where the closet stands near the upright soil-pipe, which is open at the top, it is sometimes claimed that there is no danger of gas finding its way into the room against the rush of water. But even were this the case, the removal of the odors arising from the use of the closet would be well worth the trouble and cost of introducing the ventilating-pipe.

Care should be taken that the ducts enter a flue which is always heated. In case the kitchen chimney is not warm at all times, the ducts should be heated by other means, for when the air is cooler than that outside, the draught is as sure to be downward, as it is to be upward when the opposite condition. prevails.

A gas jet or an oil lamp may be used for heating. A jet which gives out a blue flame-known as an air burner—is best, as it makes no soot and gives more heat for the same amount of

gas consumed than one which has a yellow flame. A jet of this kind, which burns one foot of gas per hour, is sufficient to heat a pipe that will ventilate several wastes.

In case the sewerage of a building is connected with a cesspool, the latter should have a grating at the top. The soil-pipe should have no trap, and should be taken out through the roof. There should be provision made for heating the upright soil-pipe in order to establish a current down through the cesspool and up through the soil-pipe to the outer air. (See cut No. 3.)

The first-mentioned plan of ventilation may be used in connection with a cesspool by making the heated flue or duct of sufficient capacity to cause a draught through the cesspool, as well as through all the wastes. In this case there should be no traps.

It has been asserted that discharging sewer gas through the chimneys is not ridding ourselves of it, as it is liable to settle down upon the dwellings and be as dangerous as though coming in by the shorter route, but there is probably little danger from this source. The heat in the flue has a tendency to destroy the gases, or at least to rarefy them so that they do not settle, but are thoroughly diffused.

It is also generally accepted that the more injurious or sewer gas is very volatile, while the heavier carbonic acid gas is not hurtful in small amounts.

Unless the cellar of a dwelling is ventilated at all times, the air will find its way through the floors and partitions to the rooms above. Most cellars have always more or less mould about them, and usually during the winter months the only escape for the air is through the rooms above. To be well ventilated the cellar should have, besides various openings above the ground directly to the open air, a large flue passing from near the cellar floor out through the roof. This need not be heated, as the warmth of the house will insure an upward movement of air.

To ventilate the kitchen there should be a flue of good sizesay two feet square-as near the top of the cook-stove or range as convenient, extending upward into the open air. This may be arranged so that it can be closed at the top when the kitchen is not in use. A hopper-like arrangement at the bottom to

gather the vapors from the cooking utensils upon the stove is also useful.

During the colder months, when the temperature of the external atmosphere is from 20° to 80° lower than that required for comfort inside of our dwellings, we must provide for artificial heating and for the ventilation of the various rooms in addition to the provisions already mentioned.

The question of how much heat and air is necessary, not only for comfort but also for health, is difficult to answer in definite terms. The factors of the problem are so numerous and so variable that tables without number would be necessary for the solution of every case. However, we can determine by our senses when we are apparently well supplied with fresh air of an agreeable temperature, and we can then adopt such measures as experience dictates to keep ourselves comfortable. Our feelings are usually very reliable in offering indications of the condition of the air, although a person may remain so long in a vitiated atmosphere, or the change in the air may be so gradual that his senses fail to warn him of his danger, and it is only after a visit to the purer air that the ability to detect such causes of discomfort returns.

Dr. R. Angus Smith, whose original researches have added much to the existing knowledge of this subject, and whose chemical experiments and tests have been particularly valuable, says, "I believe man has learned nearly all he knows of ventilation by attention to these feelings, whilst chemical analysis is attempting to struggle after him, and is constantly finding itself behind in the race."

We are indebted to Dr. R. Angus Smith, E. A. Parkes, M.D., and to F. A. Coburn, architect, for valuable assistance.