Popular Science Monthly/Volume 54/March 1899/Scientific Literature
SPECIAL BOOKS.
Professor Bailey shows, in his hook on the Evolution of Our Native Fruits[1] that the value of the native American species has not yet begun to be adequately estimated, and his narrative carries the conviction that the possibilities to be realized from their development are totally undreamed of. De Candolle made the astounding assertion, in his book on The Origin of Cultivated Plants, that the United States only yields as nutritious plants worth cultivating the Jerusalem artichoke and the gourds. "They had a few bulbs and edible berries, but have not tried to cultivate them, having early received the maize, which was worth far more." "And yet," Professor Bailey answers, "the American grapes have given rise to eight hundred domestic varieties, the American plums to more than two hundred, the raspberries to three hundred, and various other native fruits have a large progeny." Three motives, the author says, run through his book: An attempt to expound the progress of evolution in objects which are familiar and have not yet been greatly modified by man; an effort to make a simple historical record from unexplored fields; and a desire to suggest the treasures of experience and narrative which are a part of the development of agriculture. The studies of which the book is a fruit were begun more than ten years ago, and were pursued with original sources where they were accessible, and at the cost of much labor and travel. The story begins with the grapes. The cultivation of native grapes, which are singularly abundant and various in the wild condition, began after several attempts on the large and on the small scale to make foreign grapes profitable had failed. Nicholas Longworth, of Cincinnati, who did more than any other one man to promote it, sought for wine grapes. After several varieties had been tried with more or less success, the Catawba and the Concord were introduced, and the cultivation was established and became important, but no longer with wine-making as its chief object. Now we have a large variety of grapes—characteristic, finely flavored, and adapted to numerous uses in wines and desserts. Plums are mentioned in the early records nearly as frequently as grapes. There are five native types from which diverse varieties have arisen, the greater part of them of fortuitous origin. The native cherries have not yet been very hopeful of promise, except the dwarf species, which seem "destined to play an important part in the evolution of American fruit." Five types of native apples are known, from which a number of named and worthy varieties have arisen, by Nature's propagation, not man's; and the author anticipates great benefits to be derived from the very gradual and undemonstrative insinuation of native blood into the domestic sorts. The story of the cultivation of the raspberries, blackberries, dewberries, strawberries, gooseberries, currants, and mulberries tells of much patience and skill applied to the production of results in the benefits of which all may share, and which have undoubtedly added to the sum of human well-being. There remain still many fruits, the 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,[2] 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 currents, air movements, depth of water, etc., render these theories practically valueless for use in tidal calculations.
In the following section Dr. Draper shows how, by means of Lord Kelvin's "harmonic analysis," which separates the tide-generating forces of each kind into a number of ideal components, results of practical value are obtained. In Chapter XIII a very ingenious instrument for tide prediction which has been in use for some time by the Indian Government is described. The recording part of the machine is simply a paper-wound drum, on which a pencil point makes a graphic record. When the tides of a given port are desired, it is only necessary to set the instrument according to the tidal components, obtained by harmonic analysis and the time chosen for the beginning of the tide table, and then start it at the proper moment. It takes about four hours to run off the tidal curve for a year. This curve is then measured, and the year's tide table readily made out. Dr. Darwin informs us that a very similar instrument is now in course of construction for the United States Government. The remainder of the work consists of a more detailed discussion of the various disturbing influences which interfere with the simplicity of tidal movements—displacement of the earth's axis, earthquakes, etc, a long discussion of tidal friction, a study of the laws of rotating liquid masses, the nebular hypothesis, and finally a chapter on Saturn's rings. The text in many places will be found difficult to understand by the general reader, despite the author's efforts to fully and simply explain every point, and it seems questionable whether a thorough discussion of tidal phenomena can be made simple enough for the layman's comprehension. The volume can not be read by any one, however, without instruction, and is much the best general discussion of tidal phenomena which we have seen.