Page:Popular Science Monthly Volume 18.djvu/780

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formed by a hunting expedition to the next Sierra Nevada than by all the homilies of Fray Gerundio. Like depraved humors, prurient propensities yield to active exercise more readily than to physic and prayer. Hunting tribes are generally continent, stalwart, and comely; wood air is a cosmetic; the finest types of the human form are not found within the precincts of the Palais Royal, but in the Caucasus and the Kentucky forest counties.

Enjoyable winter excursions are a privilege of the rich; still, a pair of good skates make a convenient pond or a small river a great blessing. From a sanitary point of view, the neighborhood of larger streams is not so much of an advantage; besides being the terror of parents during the skating season, a big river is apt to render the contiguous lowlands more or less malarious, especially after every inundation. In snow-bound villages children have to depend mainly on in-door exercises; cold air, however, is a powerful tonic, and a two hours' snowball-fight will generally suffice to vitalize a juvenile constitution for a couple of days. Mountain air, too, is a peptic stimulant, and pedestrian excursions are doubly invigorating if they include a good deal of up-hill work.

For those who wish to select their dwelling-place with regard to the hygienic interest of their children, the best location is, therefore, on the whole, the bank of a small river in the neighborhood of a large mountain-range.

By Professor E. S. BURNS.

CHRONOLOGY is the science of the measurement of time, of ascertaining and fixing dates, which constitute the landmarks by which the mind is guided in its backward course through the long vista of years, and enabled to locate and fix the events of history, the knowledge of which would otherwise be a confused and wellnigh useless attainment. The advanced state of astronomical science and the experience of those who have gone before us have enabled us to reduce all that pertains to this subject to so complete a system that we lose sight of its magnitude and importance; we forget the slow progress and toilsome research which the great minds of past centuries had to undergo to reach the present state of correctness. To appreciate even faintly this magnitude, we must transport ourselves backward a few thousand years, and forget, if we can, the improvements of modern astronomy, the developments of mathematics, and, above all, the universality and ubiquity of modern almanacs.

The first and most obvious division of time is the day—the time required for a revolution of the earth upon its axis—which could not