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Page:Popular Science Monthly Volume 54.djvu/727

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SCIENTIFIC LITERATURE.

improvement of which has hardly begun, and which offer a promising field for experiment—the persimmon, pawpaw, whortleberry, buffalo berry, barberry, and nuts. The whole history of the improvement of American fruit is interpreted by Professor Bailey as showing that in nearly every case the amelioration has come from the force of circumstances, and not from the choice or design of man, principally because foreign species did not do well and something adapted to American conditions had to be found. Yet much skill has been shown in recognizing the good qualities of the native species, and in giving them conditions favorable to improvement. For the future the author believes that the best results at the amelioration of any species are to be expected by working with the highly improved forms rather than with the original wild stock. We need, he says, a greater range of variation, more divergent and widely unlike varieties, and more incidental or minor strains of the most popular and cosmopolitan sorts. Professor Bailey finds the greatest satisfaction in his book in the record of the men who have been instrumental in introducing the improved fruits. No men have been greater benefactors to our country than these, who have done the equivalent of making two blades of grass grow where only one grew before, and have added to the healthful sum of pleasure and content.

As Professor Darwin truly says, a mathematical argument is, after all, only organized common sense; but, unfortunately, it is usually in such a highly organized form as to be beyond the intelligence of the average reader. In the present volume,[1] however, the author has wonderfully simplified a most intricate and difficult mathematical subject, and really seems to give some justification for the above generalization.

The first chapter of The Tides is devoted to defining them and describing methods of observation and study. The curious tidal movements in lakes, called seiches, which were first systematically studied by Professor Forel on the Lake of Geneva, are taken up in the second chapter; an account of Forel's work is given, and the statement made that similar researches are now under way on other lakes, notably that of Mr. Denison on Lake Huron in this country. Tides in rivers, including an account of the curious tidal phenomenon known as a "bore," are next described, the laws governing their variation and the ways in which they differ from the tides of the open sea being carefully laid down. A brief historical chapter, containing some curious extracts from Chinese and Icelandic literature, is rather instructive anthropologically than tidally. The three following sections are taken up by a study of tide generating and modifying forces, and include an interesting account of the experiments made some years ago by Dr. Darwin and his brother, in an effort to measure tidal forces by means of the bifilar pendulum, which is now such an important agent in seismological investigation. Chapters IX and X give an account of the equilibrium, and the dynamical theories of the tide-generating forces, and are chiefly accounts of the devices by which mathematicians have endeavored to bring artificial order out of the actual chaos. The great complexity of this portion of the subject; the variety of forces operating to produce the tides, the sun, the moon, the earth's rotation, etc.; and the number of retarding and confusing elements, friction, interposed land masses, river


  1. ↑ The Tides; and Kindred Phenomena in the Solar System. The Lowell Institute Lectures for 1898. By George Howard Darwin. New York: Houghton, Mifflin & Co. Pp. 378. $2.