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Page:Popular Science Monthly Volume 38.djvu/877

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and Wisconsin Rivers. To hold the water subject to control, a dam is to be constructed across the lowest rim of each basin—that is, that part of the rim which is the drainage outlet of the basin. In each case the discharge gate of the reservoir will have an area not less than the cross-section of the stream at low water. It is shown that 95,572,000,000 cubic feet of water may be stored away in the reservoirs on the Mississippi alone. The reservoirs already completed on that stream show an actual capacity of nearly 5,000,000,000 cubic feet more than their estimated capacity. Not all of this water is available for storage, however, as 46,000,000,000 cubic feet are required for the constant flow between May and December, leaving a minimum of 49,000,000,000 cubic feet (with a possible ten per cent more) available for storage. Calculations show that with a low stage of water continuing for four months, the amount to be drawn from the reservoirs would aggregate only 42,000,000,000 cubic feet against an actual amount of 49,000,000,000 cubic feet in the reservoirs. This, if we consider the increased actual over the estimated capacity of the reservoirs, would give 5,800 cubic feet per second that could be spared, while only 4,400 are needed. Including also the reservoirs that might be constructed on the Wisconsin, Chippewa, Crow Wing, and Fox Rivers, the available supply could be increased to a possible 40,500 cubic feet per second for ninety days. The reservoirs, once they are constructed at the sources of these streams, will give a much more uniform volume in the Mississippi, so as to insure a fair stage on all bars, and will also add several hundred miles of navigable waters to the great system of river transportation. These streams are mentioned, not because they are more important than the large rivers below, but because they are the outlets of hundreds of large lakes in the northern part of Minnesota and Wisconsin. Their freshets may be an important factor in the more disastrous floods of the lower Mississippi.


Glacial Action in Niagara River.—Prof. G. W. Halley dissents from Prof. Gilbert's theory of the history of Niagara River, and believes that glacial action was an agent in the formation of the channel. In 1840, he said, a large surface of rock on the bank of the river was removed at different points for the purpose of making certain improvements, and was found to be deeply scored while the vicinity furnished many granite bowlders. Three branches of drift stone and gravel are developed at Lewiston, and the evidence of glacial action is abundant. These and other facts which the author mentioned point, in his opinion, to the existence and progress of a grand terminal moraine, which was once the boundary of an immense inland sea. So far from the Niagara River carrying no sediment, as Prof. Gilbert assumes, and as one who visits it in summer might be justified in supposing, one who lives near it many years may see its waters running for ten days at a time with a dirty chocolate or dark amber color, and charged with great quantities of sand, gravel, and silt; and could hear in the rapids the gravel and pebbles grinding and scratching their way along the rough bottom. The vast dense bar at the mouth of the river on Lake Ontario is overwhelming proof of its immense scouring properties.


Value of Science in Industries.—In his paper on The Development of the Coal-tar Color Industry since 1880, Dr. W. H. Perkin named various coloring matters which had been discovered during the last ten years, and illustrated his remarks by experiments with different colors. Germany still holds the first position in the market, both as to quality and quantity, but the competition of Swiss, French, and English manufacturers with that country has been steadily increasing. Several years ago the author had expressed an opinion of the necessity of scientific research being made an important part of the training for chemical students, so that highly skillful chemical men imbued with a spirit of investigation might be produced, not only to fill chemical chairs, but also to occupy important positions in chemical works. Hitherto not so much progress had been made in this direction as was desirable, and he feared that this was to some extent due to manufacturers not having as a body sufficiently realized the great importance of employing such men in their works. Thus, the demand being small, the supply necessarily corre-