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Page:Popular Science Monthly Volume 24.djvu/660

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THE POPULAR SCIENCE MONTHLY.

upon the heat-supply. By constringing the cutaneous vessels, it congests the internal organs and weakens the heart, while it requires some time to restore the equilibrium of the circulation. In rainy weather, the result is still more detrimental. In a climate like ours, exposure to rain is at all times fraught with danger to health, and particularly when one sits still in wet or damp garments for any great length of time. No recess out-doors, on a bitterly cold or rainy day, should be the rule, and gymnastic exercises, calisthenics, motion-songs, etc., should take its place. Every grammar-school should have one room fitted up as a gymnasium. There is a certain amount of nerve-energy that is accustomed to find outlet in the muscles, and, if unduly repressed, it will often break through the strictest discipline and cause the teacher much annoyance. It must not be forgotten that muscles were not created to be kept still during waking hours, and, when kept at rest an hour or two, a surplus of energy accumulates, which recess gets rid of legitimately. It also serves another purpose admirably. Of all sedatives of the nervous system, muscular exercise is the most efficient, because physiological. It quickens the circulation, and stimulates the heart and all the vegetative functions.

After exercise, the muscles—of the hand and forearm particularly—are subject to rhythmic, automatic waves of contraction; that is, there is a tremor beyond the power of the will to control. So that writing and drawing, which require great steadiness of the hand and fingers, should never be taken up after recess, or at the commencement of the afternoon session. Of the elementary studies, mental arithmetic involves the closest application of the highest powers of the mind—drawing at once upon memory, reason, and judgment—and this may be taken up advantageously from half-past eleven to twelve. Breakfast digestion is then nearly if not quite completed, and intense application is least detrimental to the vegetative system.

The morning meal is usually light in material and amount; dinner, partaken of soon after noon (except in the largest cities), is the principal meal. It is "solid," in a physiological not less than in a popular sense, for it is most generous in amount, and usually rich in nitrogenized matters—flesh-meat, puddings, eggs, etc. After its ingestion, the digestive organs are taxed to their utmost capacity, and soon become loaded and distended with blood. The digestive system is quite extensive, and is richly supplied with blood-vessels, which are imbedded in rather loose tissue, so that they may dilate, to accommodate the sudden influx from the outlying portions of the body, together with the newly-absorbed products of digestion. The brain is thus deprived of its full supply; and if, by reason of severe study, it draws upon the circulation, the digestive organs are robbed of their needs, and their efficiency interfered with seriously. Intense application at this time does harm in another way. All the functions of the body are under nervous control. The digestive organs are mainly innervated by the