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Page:Popular Science Monthly Volume 24.djvu/659

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them permanently in the memory. The inherent vigor of the mind can be strengthened by systematic exercise, just as the muscles of a blacksmith's arm become strong and brawny by years of daily toil at the clinking anvil.

Throughout animated nature, a period of repose succeeds one of activity, both recurring in regular alternation. The vegetable world grows and blooms; then, for a season, all the vital processes stand still. Work brings weariness, which rest must dissipate. So is it with the tissues of the body; and the younger and more delicately organized they are, the sooner does toil exhaust them. Brain-matter is the most delicate of all our tissues, and nearly one third of the pure blood thrown out by the heart at each contraction goes to supply it. A tissue, when at work, has its blood-supply largely increased. When the mind is actively engaged in study, the circulation in the brain is full and active, the temperature is raised, even the face is flushed; and the more difficult the study, the more these effects are intensified. After a time, the brain becomes so engorged with blood that its activity is depressed and its energies begin to flag. The younger a pupil is, the sooner does his mind grow tired. Between the ages of six and seven, the lessons should not exceed ten minutes' duration, as young children are unable to keep their attention fixed upon one subject for a greater length of time. It may be laid down as a safe rule, that close mental application for an hour and a half will tire out the majority of pupils, and leave them unfit and indisposed to proceed further without a relaxation of at least ten or fifteen minutes.

Here the forenoon recess is indicated—not, as some imagine, simply to kill time, but as a positive physical necessity, not for the pupil alone, but also for the teacher. The worry and mental strain of governing a roomful of nervous, restless children, and teaching at the same time, no one can fully realize without actual experience.

How should recess be spent by the pupil? To reply to this, his physical condition must be considered. As the blood is contained in a series of closed vessels, it is evident that, if the circulation be increased in one portion, it is correspondingly diminished in another. When the brain is engorged, some other portion of the economy must be under-supplied. By a wise provision of Nature, the surplus is drawn from the tissue that is least active in this case, from the muscular system. The indication is to relieve the congested brain, and this is best met by muscular exercise, as a tissue in action has its blood-supply largely increased. The muscular system is of considerable extent, and the exercise that brings the most muscle into action is the most beneficial.

Therefore, daring recess, nothing can take the place of active exercise in the open air.

But if the temperature is very low, recess had better be taken indoors, for the intense cold exhausts the vitality by drawing largely