As regards height, the sudorific chambers should not be too lofty, or they cannot, on the ordinary hot-air plan, be heated with due economy. The vastness of the old Roman tepidarium would have been impracticable under this system; but with the heat radiating direct from the walls and the floors, there was no difficulty. It is far better to have a comparatively low chamber with a constant stream of freshly-heated air passing through it, than a lofty one with a sluggish current. From 10 to 15 or 16 ft. may be taken as moderate extremes of height in a public bath. The small third hot room will be less lofty if the heating-chamber be placed under it; for by raising the floor of the laconicum a few feet, so as to necessitate ascending to it by a few steps from the level of the tepidarium, one can more economically construct the furnace chamber. This latter, which I have more particularly described and illustrated in the chapter on heating and ventilation, should, if the system adopted be on the ordinary hot-air principle, be so placed that an abundant supply of fresh pure cold air can be obtained for the furnace, which, when heated, can be delivered into the hottest room above, not less than 5 ft. from the level of the floor of that chamber, and, also, where a smoke flue of ample section can be constructed. The heated air may be delivered through the gratings in the walls of the laconicum, or a shaft of glazed brickwork, of rectangular section, may be constructed against the end wall and coped at the required level--5 ft. or more above the floor line. Should the exigencies of the site separate the furnace chamber from immediate connection with the hottest room, the heated air must be conducted from the former to the latter by means of a large shaft or shafts of glazed brickwork. Similar means may have to be employed to bring the cold air to the heating-chamber, and at the mouth of this shaft some provision must be made for filtering the air before it is brought into contact with the heating surfaces of the furnace. Horizontal and inclined flues for conducting hot or cold air may be carried from point to point on rolled iron joists having tooled York slabs set thereon, the flues being constructed of 4-1/2 in. brickwork with glazed face internally, and covered with tooled York slabs. Provision must be made, in such flues, for effective cleansing, by means of iron air-tight doors. THE LAVATORIUM AND SHAMPOOING ROOM.