Page:Popular Science Monthly Volume 47.djvu/147

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been attached to it. He believes that it may be made to throw light on all the branches of science that deal with the structure of the earth—on geography, geology, paleontology, mineralogy, zoölogy, anthropology, the physics of the globe, agriculture, public works, and hygiene. In his explorations of caves M. Martel has devoted much attention to those openings which form a peculiar feature in the limestone regions of France and eastern Europe, called gouffres or pits, which have been regarded hitherto chiefly as curiosities or feeders of superstitious fears, but are almost virgin to scientific exploration. During six years, from 1888 to 1893, he explored two hundred and thirty of these gouffres and other cavities, one hundred and sixty-five of which had never been examined before, and made a large number of plans. In this work he had special regard to the hydrology, the origin, location, etc., of subterranean waters, with a view to utilize the lessons of his observations in agriculture, but did not neglect to examine carefully all the other bearings, not letting the most minute features pass unobserved. The results of his investigations have been published in a book, Les Abîmes.

Forests and Climate.—Considering the Relation of Forests to Climate and Health, Cleveland Abbe finds that while the forest does not cause increase of rainfall, its tendency is to conserve it. The forest shields the moisture from evaporation and uses less of it for its own growth than would be used for the growth of grasses or herbs, and it also conserves what is left in the soil so as to diminish, or at least regulate, the drainage into the river basins, thereby reducing the danger of destructive floods. The influence of forests extends outside of their boundaries under varying conditions. The effect of forest-covered mountains is to diminish the cold night winds and the hot day breezes in the valleys below, and to favor the formation of local cloud and rain in them. As the air that flows down the mountain side during the night from a forest has a higher dew point and a lower temperature than that which flows down from an unforested surface, therefore a less amount of cooling will cause it to form fog; hence the crops in the valley are more likely to be sheltered by the fog from dangerous frosts. The most interesting influence of the forest on the leeward side is that which it exerts by virtue of its action as a wind-break. A diminished wind means that the sluggish moving air shall be warmed up in the daytime by contact with the ground much more than would be the swift-moving air when the wind-break is absent. This reacts upon the ground, so that as a consequence both soil and air are warmer. The evaporation from the surface of the soil is also greatly diminished, in consequence of which the soil retains more moisture, and is warmer than it would be under the influence of a strong wind. At the same time, the air above the soil acquires a higher percentage of relative humidity. Thus the plant has more water at its disposal stored in the earth, while the leaves, apparently, are in less need of water, and transpire less.

Biological Laboratory at Cold Spring.—The Biological Laboratory of the Brooklyn Institute at Cold Spring Harbor, L. I., aims first at instruction. Each year a course has been given there in elementary systematic zoölogy, adapted both to teachers whose knowledge of elementary zoology is not great, and to students of higher institutes who seek a practical study of marine forms. A botanical department was organized in 1893. More advanced courses have been established, and lessons were given last summer on comparative embryology. A course in bacteriology is given by the director. Original investigation is provided for in private rooms for research, and most of the Board of Instruction and others who have been present from time to time have been engaged in personal work in that line. In addition to the regular work of the school, evening semi-popular lectures are given to the students and to attendants from the neighborhood. During the last year a department was started for supplying specimens of the common types of marine life to colleges and schools.

Lord Rayleigh on Waves.—In a lecture at the Royal Institution, on waves of water, Lord Rayleigh said that in such waves the velocity is not independent of the wave length (or distance from crest to crest) as it is in the case of sound waves, but the long waves