The mode of warming and ventilating the several apartments of the Free Academy can be easily understood by consulting Figures 2, 3 and 4. Four of Culver's furnaces are set in the basement, as shown in Fig. 3. A large quantity of fresh air from out of doors, after being warmed by these furnaces, is carried up to the several stories by pipes in the division walls, (Fig. 2,) and is admitted into the rooms at a convenient point, as indicated in Figures 5 and 6. The air of each room, as it becomes vitiated by respiration, is discharged by openings near the ceiling into the buttresses, which are constructed hollow and finished smooth, so as to constitute large ventilating flues. Each opening is fitted with one of Culver's Ventilators or Registers, with cords attached, by which the capacity of the opening for the discharge of vitiated air can be enlarged and diminished at the pleasure of the teacher. The practical working of the furnaces and flues for ventilation, secures the object aimed at-a genial and pure atmosphere at all times.

Fig. 3.-BASEMENT FLOOR.

The above cut gives an incorrect view of the exterior of the building, but a good idea of the internal arrangement of the basement story.

The author of this treatise has not been furnished with descriptions of this and the following plan, but a general idea of the arrangement of the room can be obtained from the cuts themselves, and from the description on page 232. The building contains more accommodations than any similar structure in any of our large cities, according to the cost.

APPARATUS FOR WARMING.

THE thorough ventilation, the constant and regular change of the atmosphere of a school-room cannot be secured by simply providing flues or openings, however judiciously constructed and placed, for the escape of the air which has become impure from the process of breathing or other causes. These flues will not work satisfactorily, unless a mode of warming the room is adopted by which a large supply of pure fresh air, properly heated, is flowing in to supply the place of that which is escaping by means of the flues. Among the various modes of warming school-rooms and public halls, which we have seen in full and successful operation, we select a few. in addition to those described in other parts of the work, as worthy of the particular attention of committees and others, who are looking round for a heating apparatus. We shall use the cuts and description by which the patentees and venders have chosen to make their several modes of warming known to the public, without intending to decide on the relative merits of any one mode.

CULVER'S HOT-AIR FURNACE.

PATENTED AND MANUFACTURED BY CULVER & Co., 52 CLIFF STREET, NEW YORK. Culver's Hot-Air Furnace, as described in the following diagram and explanations, is intended for hard coal, to be set in double walls of brick masonry in cellar or basement, below the rooms to be warmed.