VENTILATION OF A ROOM LOADED WITH PRODUCTS OF COMBUSTION FROM GAS, AND SUBJECT TO OFFENSIVE COLD CURRENTS ON THE FLOOR.

"In a room warmed by an open fire, there are great complaints of a current of cold air passing along the floor, while the air on the line of respiration feels heavy and oppressive, producing great restlessness, particularly when a series of gas-burners are lighted that give a brilliant illumination. This is one of the most common forms of complaint in numerous apartments, and the causes will be obvious on inspecting the accompanying figures.

The air admitted being very cold, and entering partly by a slight leakage at the window, but principally below the door, from a passage not warmed artificially, has little tendency to rise, and passes along the floor to the fire-place. The gas, however, induces a powerful current at a, Fig. 1, which ascends with force and strikes upon the ceiling, where it is soon diffused, and descends on every side as it cools. Part of it mixes with fresh air below, and is carried off by the action of the fire; the rest ascends again by a rotary movement towards the gas-burners, where it mingles a second time in the current, ascending and descending as before. The upper portion of the air is accordingly largely charged with moisture and carbonic acid gas, the principal products of its combustion.

In Fig. 2, the principal arrangements necessary for removing these evils are shown in one of the many modes by which this can be accomplished.

A free supply of air is admitted by the flue A, being drawn from a central apparatus supplying warm air. A much smaller open fire is then sufficient; with warmer air it may be rendered unnecessary. In warm weather cold air is admitted by the flue A. It is not permitted to enter abruptly at one place, but diffused at the base-board by perforated zinc, or at a panel from which it escapes into the apartment to be supplied. A vitiated air flue, B, starting at the level of the ceiling, continuously removes the bad air, and preserves fresh air at and immediately above the zone of respiration, the great object in all ventilated apartments.

A reference to the succeeding diagrams will explain many modifications that may be adopted in carrying such alterations into effect.

The primary objects in all ventilation are the removal of vitiated air, and the introduction of fresh air in an imperceptible stream. The diffusion of the entering air in a chamber, air trunk, or channel, indicated by the deeper tint proceeding from A, Fig. 2, breaks its impetus in proportion to the extent of diffusion. The warmer the air

supplied, and the more distant from A the portion of floor generally occupied, the less is the amount of diffusion required. The vitiated air may be discharged directly into the external atmosphere, or any of the arrangements may be adopted that are indicated in Chapters IV

and V."

SPECIAL VENTILATING FLUE.

The following figures, 8, 9, 10, 11, 12, explain the principal varieties of ventilating flues which Dr. Reid recommends to be introduced in all American dwellings, one or other being selected according to the local circumstances of each individual case, and provision being made for the safe application of power by heat whenever it may be desired.

"If a ventilating turret be erected on the roof of a house, Fig. 8, F, and a staircase, or any other descending channel that may be rendered sufficiently air-tight, be connected with it, then, as in the case* E, minor ventilating tubes discharging vitiated air can be led into it, and a series of gas-lights kindled above at x, when the vitiated air is not sufficiently warm without them, to give the requisite ventilating power.

Fig. 9, G, indicates a similar arrangement; a chamber in the roof receiving the vitiated air from minor channels, which communicate with all the places to be ventilated.

The ventilating turrets F and G having no great amount of heating power, in cases where the utmost effect of a ventilating shaft is necessary, and when a turret on the roof would not give the necessary heat or altitude, it is requisite to make a descending shaft for collecting and carrying downwards all the vitiated air, and an ascending shaft for giving the moving and discharging power. H, Fig. 10, points out the usual and most convenient form given to such shafts, the arrow indicating the course of the vitiated air. There is no limit to their size, nor to the number of apartments upon which a single shaft of this kind can be brought to bear, the amount of fuel used being proportionate to the ventilating effect required. The higher the chimney, the greater is the power exerted.

In climates where there are great extremes of temperature, the ventilating shaft is often so constructed as to be used in winter without a fire, the temperature of the apartments ventilated, when the external air is cold, giving the necessary power. Fig. 11, K, shows a shaft similar to H, Fig. 10, provided with a valve opening at m, and permitting vitiated air to escape without any previous descent. By

*A modification of this form of flue referred to in a preceding paragraph.

changing the position of the valve, m is closed, and an opening again restored at z, when fire can be employed to give the requisite ventilating power in warmer weather.

In many cases two descending shafts may be formed as in Fig. 12, L; or they may be multiplied to any extent, provided the aggregate power required to put as many as are wanted in effective operation at a given time shall not exceed that of the ventilating shaft.

In ordinary habitations a single flue of the usual size will be found very useful, but it is presumed that the time will arrive when no houses containing from ten to twenty rooms will be constructed without a ventilating turret, tower, or shaft from three to six feet square, according to the numbers it may be intended from time to time to invite, and the dimensions of the principal apartments.

SMALL CHAMBER FOR ARTIFICIAL ATMOSPHERES.-VENTILATED AIR, STEAM, AND

SHOWER BATH.

Artificial atmospheres may be formed in apartments on a larger scale than are indicated in the preceding figure, the means employed being proportionate to the magnitude required, and the numbers present at a given time. They are prepared most effectually by transmitting the ingredients necessary into an air channel through which a regulated current of air is made to pass. This current may be put in motion by a mechanical power, or by a heated flue. The latter is preferred for all ordinary purposes. For one person, a small chamber lighted by glazing it on one side and in front, sufficiently large to admit a chair, and allow any individual to stand erect in it, and having a platform or floor about four feet square, is sufficient for common use. An area of two feet six inches by three feet, may be substituted where it is desired to economize space and materials. In this chamber, supplied with one flue for the admission, and another for the discharge of gases and vapors, hot air, cold air, moist air, dry air, or any other atmosphere, may be conveniently applied to the system as a means of preserving health or curing disease.

The accompanying figures 40, 41 indicate a chamber of this kind, which it is recommended to provide in ordinary habitations, and also in hotels and lodging-houses, where numbers are congregated.

Seated in the chair shown in the figure, each individual can, according to his own taste, subject himself to a powerful current of warm or cold, dry or moist air. Or he can have a shower-bath of hot or cold water, or of water at any intermediate temperature.

But the arrangement is prized principally for the combination which it gives of a steam-bath, in which this powerful agent can be mixed