Page:Popular Science Monthly Volume 21.djvu/568

554 set forth in this volume must of necessity be full of imperfections. If it be asked why, being thus conscious that far more time and wider investigation are requisite for the proper treatment of a subject so immense and involved, I have undertaken it, my reply is that I have been obliged to deal with political evolution as a part of the general Theory of Evolution; and, with due regard to the claims of other parts, could not make a more prolonged preparation. Any one who undertakes to trace the general laws of transformation which hold throughout all orders of phenomena must have but an incomplete knowledge of each order; since, to acquaint himself exhaustively with any one order, demanding, as it would, exclusive devotion of his days to it, would negative like devotion to any of the others, and much more would negative generalization of the whole. Either generalization of the whole ought never to be attempted, or, if it is attempted, it must be by one who gives to each part such time only as is requisite to master the cardinal truths it presents. Believing that generalization of the whole is supremely important, and that no one part can be fully understood without it, I have ventured to treat of Political Institutions after the manner implied: utilizing, for the purpose, the materials which, in the space of fourteen years, have been gathered together in the "Descriptive Sociology," and joining with them such further materials as, during the last two years, have been accumulated by inquiries in other directions, made personally and by proxy.

information on which this report is based has been procured, so far as is possible, directly from the producers of bullion. It was not expected that completeness could be reached in this way, for many small producers would be overlooked or would fail to report, but the plan gives a nearer approach to accuracy than can be gained from the comparison of the receipts of domestic bullion at the mints and assay-offices, or from an examination of the bullion accounts of the express companies—the only other sources of information that were open. A comparison of the annual output of different States shows that the United States produces 33·13 per cent of the gold yield of the whole world, 50·59 per cent of the silver, and 40·91 per cent of the total. Of the aggregate supply of the precious metals, North America furnishes 55·78 per cent.

volume has very strong claims upon the biological student; but for the beginner, especially if he lives near the sea, it is incomparable. The art of starting a beginner aright in any branch has not yet been perfected, but Dr. Brooks has made a successful stroke in this direction for zoölogical science. The work has been planned with reference to the exigencies of systematic study, and to put the student upon the right track to attain the mastery of the subject with the least waste of exertion. Nothing is introduced that is not wanted. Generalizations and comparisons are omitted, on the principle that the beginner shall first get at the facts, in order that he may subsequently grasp and make the generalizations his own. The work is therefore not a text-book, but a hand-book of practical study, and is admirably adapted for self-instruction. In his prefatory remarks describing the work, the author says: "Most lecturers upon natural science find, no doubt, that preliminary work, the presentation of facts upon which science is based, absorbs so much time that there is no room for a philosophical discussion of the scientific aspects of the subject. I have therefore attempted to show the student how to acquire a knowledge of the facts for himself, in order to remove this burden from lecturers and text-books."

The types selected for description are, of course, but few compared with those considered in systematic works; but still they cover wide zoölogical ground, and are sufficient to prepare for more comprehensive research. In the treatment of each type the author has not attempted to present all that is known about it, but simply to guide the beginner to those features which he can find and observe for himself. And so also with the illustrations. The minute details of complicated structural figures are omitted, and only those given that it is necessary for the beginner himself to discover in his examination of the specimens. For this purpose, the illustrations are greatly superior to any we have elsewhere seen.

The book begins with the examination