=The Douche.=—A douche consists of a single or multiple columns of water directed against some portion of the body. The apparatus is complicated, and it is essential that an accurate pressure-gauge and thermometer should be introduced into the circuit of the douche. It can only be properly administered in a hydriatic establishment. In the employment of the douche three factors must be considered—the temperature, pressure, and the mass. The range of temperature employed varies from 45° to 125° F. The pressure ordinarily employed varies from 10 to 60 pounds. The mass varies according to the effect desired, and may be regulated by means of the finger, placed in the water column near the nozzle. The douche is applied by means of the rubber hose, which is connected at its proximal end with the water-supply, and at its distal end is attached a nozzle, the average diameter of which varies from 2 inches to ⅜ inch. From these a fine or coarse jet or a fan douche may be produced. The latter is formed by placing the index-finger of the hand holding the nozzle upon the lower border of the outlet, producing an expansion of the otherwise solid jet into a fan-shaped stream. The mechanical effects of the douche are derived from atmospheric pressure, and this is of more importance in the effects produced than the temperature. The Scotch douche consists of alternate streams of hot and cold water. The general cold douche is the most powerful of all the tonics; the warm or neutral douche is sedative; the very hot douche is frequently followed by atonic reactions. _Rationale of the Douche._—The douche is a thermic massage. Since the douche is a sorbefacient of pathologic products, the French have availed themselves of its use to aid the body to throw off an excess of uric acid, fatigue toxins, etc. It has been demonstrated that a rain douche of 50° F., under a pressure of two atmospheres, increases threefold the work that the muscles are capable of doing, while the Scotch douche, oscillating between 98° and 53° F., doubles the working capacity of the muscles. Even tepid douches increase the working capacity of the muscles, while a tub-bath of the same temperature is without decided effect. The pressure under which the douche is given adds a powerful element, which is absent in other hydriatic procedures. The percussion and vibration affect the vasomotor system much more powerfully than any form of still bathing. The power and action of the heart are greatly improved by the use of the douche, the capacity of the lungs is increased, and the digestion is improved.