Page:Popular Science Monthly Volume 39.djvu/733

Rh people, but positively exult when they reduce those of foreigners. And, when one nation has injured another in this way, that other is now very likely to strike back by means of "retaliatory legislation." Americans and Europeans have sunk to the morality of the Chinese, who regard the sufferings of all but themselves with amusement and pride, and any one who talks of neighborliness and consideration for other nations is set down as too sentimental to meddle with practical affairs. Strange to say, the fact that foreign workmen are in want and misery has been urged as a reason for trying to injure them further. Even the socialists, who proclaim the brotherhood and equal rights of man, are very apt to limit these principles by geographical boundaries. But the further a pendulum swings from the upright position, the sooner its return may be expected. Hence it is quite likely that a new era is soon to dawn, in which humanity shall no longer be dominated by geography.

Dry Denudation.—Dry denudation is shown by Prof. Johannes Walther, in his book on Denudation in the Desert, to be a process of considerable geological importance. The author points out that no part of the African desert is absolutely rainless, and that, as the storms, though rare, are heavy, the mechanical effects of water are more marked than they would be in a region where precipitation was more uniform. But in a desert, where the absence of plants and of soil exposes the rock to the effects of atmospheric variations, changes of temperature are yet more potent in causing denudation. These changes, owing to the dryness of the air, are very great. The diurnal range may be 30° C, and the annual range as much as 70° C. By the constant expansion and contraction due to these variations, the rocks are split, and the results are more important in producing denudation than are chemical changes. Illustrations are given to show how rock-masses in the desert are destroyed by heat and cold, wind, and drifting sand. The surfaces of old walls are corroded; strata of different hardness in the face of a cliff are worn back unequally; masses of rock are isolated, and the blocks and pillars are carved into strange forms; denudation, in short, seems to proceed as actively in a desert as in a damp climate, and along very much the same lines. Isolated hills of tabular form are also characteristic of desert denudation. Such hills may be either on a large scale—outlines of an extensive plateau—or on a small one, like models, but a few feet high. In each case the cause is the same: a harder stratum at the top has preserved the softer material below. The author also describes the valleys of the desert, usually dry, and the cirques which, as was pointed out some years since by Mr. Jukes Browne, seem to occur in the deserts of Egypt even as in regions where ice may be supposed to have acted. "The description of the latter forms is important," writes T. G. B. in Nature, "since it indicates that there is not that necessary connection between glaciers and cirques which some geologists seem to have imagined."

The Teacher's True Power.—The extreme elaboration of system in school, says State Superintendent Sabin, of Iowa, gives us symmetry and uniformity, but it is at the expense of growth. It promotes smoothness, prevents friction, and furthers exactness of detail, but it crushes out all life, energy, freshness, and enthusiasm, and exalts itself to the chief place in the school. The child is forgotten in the worship and homage which is paid to the system. We sometimes speak of teaching the child to think. It is as natural for a child to think as it is for a tree to grow. It is not the part of the teacher to wake up the mind, but to avoid putting it to sleep. Give the child the same freedom to think and observe that the street Arab has in his games, only guide him with skill; take advantage of his curiosity and wonder; take advantage also of what he already knows, and do not attempt to teach over again what he has already learned, and he will startle you by his progress, and by the readiness with which he will profit under your instruction. There is no place in which the individuality of the teacher can so make itself felt, and in which the individuality of the child is so thoroughly alive, as in the primary room. The author does not object to the rigid examination in the case of young teachers; but, when that is once passed, the only conditions