Page:Popular Science Monthly Volume 40.djvu/145

Rh United States Department of Agriculture. North American Fauna. No. 5. Pp. 127.

United States War Department. Charts showing the Average Monthly Cloudiness in the United States. Twelve Charts, folio.—Charts showing the Probability of Rainy Days. Twelve Charts, folio.

University Extension. Monthly. Philadelphia: J. H. Shinn. $3 a year.

Whelpley Dr. H. M. A Course in Microscopical Technology for Colleges of Pharmacy. From Proceedings of American Pharmaceutical Assoc. Pp. 3.

Wiley, John, & Sons. Catalogue of Text-books and Industrial Works. Pp. SO.

Wilson, Sir Daniel. The Right Hand: Left-handedness. Macmillan & Co. Pp. 215. $1.25.



Artesian Wells and their Flow.—That part of the definition of an artesian well given by the Department of Agriculture that includes all subterranean waters which, on being reached or opened from above, are found to flow by pressure to a higher level than the point of contact, is accepted by Mr. R. Ellsworth Call, in his preliminary paper on Artesian Wells in Iowa, as complete in itself and as properly defining artesian water. Artesian flows may be variable, that is, may exhibit sometimes increased and at other times decreased flows of water, but the artesian characters are still very marked. Originally all artesian waters are meteoric, that is, are all waters which reach the earth by precipitation as rain. That they shall percolate to lower strata, be included between impervious strata or layers of clay or close-textured rock, is a necessary condition. But the total water thus held in confinement has a definite relation to the catchment basin on the one hand and to the total annual rain-fall on the other. It is easily seen, then, that artesian waters may vary with the season; that in dry seasons, when the wells are shallow, they will soonest show decreased flow; that in a series of years when the precipitation is far below the normal the artesian areas may entirely fail, again to present good wells when the fall of meteoric water reaches the normal or rises above it. Wells may then, in a certain sense, be temporary and still be artesian. In the case of the deep wells, those that lie far below the range of variation from causes connected with the variable factors of annual character that mark shallow wells, artesian flows are apt to be more constant; but even here there are certain variable features which show differences through longer intervals of time. No artesian basin exists anywhere, but it will be found necessary, sooner or later, to control, by mechanical means, the total flow or "output" of the several wells. The waters are bound to be exhausted in the long run if there be no well-planned governing relation between the consumption and the known sources of supply. The deepest and the largest flowing wells will sometimes be taxed beyond their "life," and then, for a time at least, they must be allowed to rest. No owner of artesian wells in the glacial districts, where the wells are shallow, can afford to allow his well to flow and the water to be wasted.

Different Effects of Denudation.—Describing the old, or abandoned, fields of the south. Prof. W J McGee spoke, in the American Association, of the different aspects presented by the results of denudation according to the situations of the fields. When the tracts are low or gently undulating, they are quickly clothed with vegetation; but when they are hilly and high, the ravines or deepened gullies invade the hill slopes and uplands, until in some cases the entire soil is washed away and the verdure-clothed surface is transformed into a glaring sand, while the bottom lands, once the most fertile of cotton fields, are clogged with the sand swept from the hills until they, too, are ruined for agriculture. The reasons for this accelerated denudation may be sought for in the relations which geologists have found to exist between the elevation and the configuration of lands, their climatal conditions, and the character of their vegetation. An area standing high above the base level for a considerable period assumes a rugose configuration. There is also a configurative characteristic of the prairie and another characteristic of the woodland, the latter being more rugose; and the geologist trained in this line of investigation can discriminate at a glance between the lands cleared of forests by human agency and those that are naturally grass-covered. The configuration of Mississippi and other parts of the southern United States indicates considerable altitude above base-level and an originally forest-covered condition. The surface slopes are too steep to withstand the action of. the storms and streams when the forest covering is removed. It is true that 