It has been found by cruel experiments on young puppies that sleep is more necessary to them than food, as they die after being kept awake four or five days, but may live ten or fifteen days without food. They easily go to sleep when their heads are level with their bodies, and they will not go to sleep with their heads lower than their bodies: of course, the raised head drains some blood out of the brain. This is the reason that heat or extreme cold, both of which bring the blood to the surface and drain it away from the brain, will often produce sleep. That is why the cowboy likes to sleep with his feet to the fire. On the other hand, the demand on the heart of cold hands or feet for more blood to keep them warm may make the heart pump so strongly that it sends more blood to the brain and keeps one awake. So also joy, anger, or anxiety cause a flow of blood to the brain and hinder sleep. Becker and Schuller have treated insomnia by wrapping the entire body in wet sheets and also by applying cold compresses to the head. This last device is used by students, with doubtful success, “to keep the brain cool”; it is sometimes affected because it looks like working hard. Sometimes an ice cap, a double rubber cap filled with cold water, will bring sleep. The Russian nobles used to make servants scratch their heels for a long time; our ladies have their hair brushed; and A. H. Savage-Landor says that Corean mothers put their babies to sleep by scratching them gently on the stomach. I have tried this rubbing, rather than scratching, with great success. Spanish women rub the children’s upper spine to put them to sleep. Light exercise before lying down is often a good expedient. Sometimes a pillow of heated hops or of balsam pine needles will induce sleep. To change the hour of going to bed occasionally, yielding to apparently untimely drowsiness, often helps, as it accustoms us to gain sleep at irregular times. To “relax,” to let the muscles become perfectly loose, is an art, though it should be natural to one going to sleep. Mrs. Richard Hovey recommends shaking the fingers, letting them hang loose like a bunch of strings of beads, and extending the movement to the wrist, arms, feet, and legs. This is the best form of calisthenic exercise for sleeplessness. It aids us in getting limp so as to lie at ease. CHAPTER XVII MORE DEVICES FOR GOING TO SLEEP Oh Sleep! it is a gentle thing, Beloved from pole to pole. COLERIDGE.