This circulation of air will exist in any bath heated on the modern system--that is to say, where freshly-heated air is passed in in sufficient quantity. It is a natural result, and tends to distribute the heat more equally. The back-flow is only objectionable when a door is opened direct from the heated shampooing rooms to a cooler apartment, as the plunge bath chamber. The bather standing in a line between the doorways may then feel a cold draught. To guard against this, double doors, with a small lobby between, should be provided to any means of communication with a cold chamber. A set of hot rooms could be constructed so that the bather would be in the top current of air that flows from the heating apparatus. By reference to Fig. 11 the reader will understand that by the provision of a platform or grating midway between the floor and ceiling this end would be attained. The atmosphere of the sudatorium must be perfectly free from vapour. "Perfect dryness of the air," says Mr. Urquhart, "is indispensable to the enduring of a high temperature.... This dryness is further requisite for electrical isolation. With vapour in the chamber an atmosphere is created injurious to health and conducive to disease. It is the very condition in which low, putrid, and typhus fevers flourish. The electrical spark will not ignite in such an atmosphere, and the magnet will lose its attractive power. We all know the difference of our own sensations on a dry and on a damp day." CHAPTER VI. WATER FITTINGS AND APPLIANCES. The water-fittings of a Turkish bath include a boiler of some form for heating the water, a cold-water cistern, and a hot-water tank; supply-pipes, flow and return pipes, and branch pipes; lavatorium fittings, comprising bowls, basins, and cocks; douche room fittings, as the "needle" bath, shower, douche, spray, and "wave" baths; a warm shower-bath for bathers entering the bath, or desiring such a shower at intervals; and the fittings of the plunge bath. In addition to this there may be required a drinking fountain in the tepidarium, and an ornamental fountain in the frigidarium; lavatories in various positions; and, possibly, fittings and appliances for the laundry.