The _douche_ is a name given to a stream of water, either hot or cold, which is made to fall heavily or with force upon a part. It acts partly by the force of mechanical impact, and partly by its temperature. It is a very exhausting method of treatment, and must on no account be used too long. A column of water 12 feet high, allowed to fall upon the head, is so painful that Esquirol, who submitted to it, described it as resembling the continued breaking of a column of ice on the head, followed by a feeling of stupefaction, which lasted an hour afterwards. The douche was formerly much used in lunatic asylums, and was regarded as a specific against delusions, the unhappy creature possessed by delusive ideas being held beneath the douche until he recanted; and such was the agony thus caused, that the mere threat of the douche was often sufficient to control the wildest of maniacs. Those who have undergone the process of “shampooing the head,” as practised by the hair-dressers of our time, will remember the effect of a stream of cold water allowed to flow upon the head for too long a time. The most powerfully stimulating action is obtained by the use of the _Scottish Douche_, which consists in the alternate use of streams of cold and hot water. By the hot stream the “reaction” after the cold stream is greatly encouraged. In most of the swimming baths to be found on the Continent, a pump is provided, in order that a patient may himself apply the douche to any joint requiring it, and at the same time encourage his reactive glow, by the exercise of pumping. In most great bathing establishments two douches at least are provided, one called the _descending douche_, which may be applied to the head, shoulders, trunk, or limbs; and the other called the _ascending douche_, which is designed for throwing a stream of water into the bowel, a method of treatment which is advocated for conditions which it is unnecessary to discuss in this place. _Hot and cold affusion_ are merely mild forms of the douche. The _shower bath_ differs from the douche only in the division of the stream of water by causing it to flow through a suitable colander. This method of treatment is severe and exhausting, and must be used with caution, especially with weakly people. The _needle bath_ is merely a general shower bath. The bather stands within a coil of pipes which are finely perforated, and the water impinges in finely divided streams simultaneously upon every part of the body. It is a powerful general stimulant. The _rain bath_ consists in the letting fall of large drops of water from a great height upon the part which it is wished to affect.