with warming, has been adopted in the Aberdeen Public Library, which the writer has had the opportunity of testing, and which is most satisfactory, both in summer and winter. The following account is condensed from a paper read by the librarian at the sixteenth annual meeting of the Library Association:—
The building consists of three main floors, each about 18 feet in height, and 75 by 45 in area. In the basement floor there is a small room, with an opening on one side to the outer air 36 square feet in area. All the air supplied to the building is drawn through this opening by a Blackmail fan 5 feet in diameter, propelled by a gas-engine of three horse-power. The fan is placed at the entrance of a large duct, from which branch off other smaller ducts to the several floors. The incoming current of air is first drawn through a screen of manilla hemp, which is kept moistened by an occasional automatic flush of water, and so all dust, soot, and other atmospheric impurities are effectually excluded. In the winter this incoming current of air, after passing through the screen, traverses a large coil of hot-water pipes, and is suitably heated prior to entering the rooms. In the rooms, at a height of six feet from the floor, are oblong openings to admit the air thus screened and warmed. The outlets for vitiated air are grated openings, placed at intervals in the walls close to the floor; these lead by several small shafts into one large central shaft, with exit at the roof of the building. When the apparatus is at work the fresh air is
