below the roof of the house, rather than at the chimney heads, in order to prevent the possibility of smoke being over brought down by reverse currents; and an advantage is likewise gained in protecting the attic story from the cold which would otherwise be communicated from the roof during winter. The continued supply of fresh air to the lower part of the house, to replace that which is carried off by the ventilators and by the chimneys, is brought in from the garden behind the house by a passage, the sectional area of which is eight square feet. The cold air admitted by this passage (or by another similar one from the front of the house) is made to pass over a stove in a lower chamber having a surface of nearly ninety square feet, so that a temperature of from 64° to 70° Fahr., can thus be imparted to the air. In very cold weather, 70° is occasionally given to compensate the cooling effect of the walls and glass windows, so as to preserve an equable temperature of 60° throughout the house; but the usual temperature of the air issuing from the stove is as low as 64°. The whole of this air is discharged into the well of the staircase, which forms a reservoir from whence the rooms draw the quantity required to maintain the upward currents in the chimneys and in the ventilating flues. The air in the staircase finds its way into the apartments by masked passages, of four or five inches wide, and four feet long, over the doors, and by openings an inch in width left under each door. The sectional areas of these passages are more than equal to the areas of the chimney and ventilating flues; there is, therefore, no rarefaction of the air within the rooms, nor any tendency of the external air to enter at chinks of windows or other irregular apertures. The course of the air, from the great aperture over the stove, through the staircases, over and under the doors, into the rooms, thence through the ceilings, and upwards by the escape flues, forms a continuous series, in which all the air for all the rooms comes from one central point, and is raised at that centre to the precise temperature required. The quantity of escape is regulated by hand, by means of throttle-valves at the mouth of each escape flue; hence, by opening or shutting each throttle-valve, the rate of the ventilating current is augmented or diminished. The kitchen is ventilated on the same principle as the upper rooms. One flue proceeds from the ceiling over the fire-place, and another from over a gas-cooking apparatus. The first of these is built in the gable, close to the smoke flue; and the second passes up near the back of the water cistern, so that the constant ascent of the warmed air may by its vicinity prevent the water in the cistern from freezing in the winter.