The respiratory movements are diminished during sleep, and at the same time there is a large accumulation of blood in the splanchnic veins, so that, particularly when there is any tendency to difficulty with the breathing at night, the trouble is greatly lessened by filling the lungs with pure air just before retiring. It is necessary, first of all, to learn the art of breathing, to be able to dissociate the clavicular, the costal, and the diaphragmatic. By clavicular breathing is meant the raising of the collar-bone and shoulders as high as possible by means of a slow but deep inspiration—this expands the apices of the lungs; costal breathing is the throwing out and expanding the chest to its utmost capacity, and so enlarging the chest in its transverse and anteroposterior diameters; diaphragmatic breathing is the depression of the diaphragm and the protrusion of the abdomen without raising the lower ribs. The last is the most readily learned in the supine position; the bed supports the weight of the body, so that the individual is able to concentrate her entire attention on fixing the bony thorax, depressing the diaphragm, and protruding the abdomen at every inspiration and retracting it to the utmost with every expiration. This, of course, develops and gives tone to the abdominal muscles. When the woman has conquered these first principles of respiration, she is ready to put them into practice in the standing posture. They should be learned before a mirror, and after that taken before an open window. The hands should be placed on the hips; first elevating the collar-bones and the shoulders to the utmost, while still holding the breath, she expands the chest, always breathing in from above downward, and, lastly, the diaphragm is depressed. With the lungs thus expanded to their utmost capacity, the breath is held as long as possible, then the lungs are emptied by an abrupt and forced expiration. These exercises should be repeated at first ten times, gradually increasing to thirty times. It is well to take one or two ordinary respirations between the forced ones. It will be found that, as these exercises proceed and the lungs are filled with purer air, the breath can be held for a longer period of time, and that with practice the length of time that the breath can be held is greatly increased; it should be held for half a minute. Public speakers, singers, and divers are all skilful in this respect. When these simple breathing exercises have been mastered, breathing exercises can be combined with other exercises, which have as their aim the development of the muscles of the chest. Reading aloud, singing, talking, laughing, are all good exercises for developing the capacity of the lungs.