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708 science, and who desire to know more. Curiosity and culture are in effect convertible terms: the wish to know is the first condition of knowing. To many who are in this stage of culture, but who have neither the time nor faculty for following up closely the ever-widening circle of advanced thought, it may be interesting to get some general and popular idea of some of the unsolved problems which have been raised by modern science, and are occupying the thoughts of the men who lead its van." To meet the want defined in this passage is the object of the present volume. The questions which the author discusses in his earlier chapters relate to the past history of the earth and other cosmic bodies. These are, How long has the sun been giving out heat enough to sustain life on the earth? What is the universe made of? What has been the climate of the earth in geologic times? When was the Glacial period, and how long did it last? From these topics he passes to the consideration of the antiquity of man and the method of his origin. A chapter is devoted to "Animal Magnetism and Spiritualism"; several religious questions are then taken up; and, finally, certain economic problems are considered. The religious questions are, whether agnosticism is reconcilable with Christianity; how great a historical element there is in the Gospels; and whether the skepticism of the present day justifies pessimism. "The Creeds of Great Poets" are also passed in review. First of the political and economic essays is an analysis of the reasons for the tension which keeps Europe constantly armed; the others deal with the financial problems of England, and the increase of population with reference to the food-supply of the world. In the case of each problem which he raises, Mr. Laing makes evident what solution he deems most probable. His discussions show a thorough knowledge of and sympathy with the scientific enlightenment of the times; and, in regard to those questions which man must answer in the future, he is generally confident that science will be able to give a beneficent solution. The only exception is in regard to the food problem, where he can see relief only from a diminished birthrate or an increased death-rate, and the idea of discovering new ways of producing edible products is not mentioned.

work originated in a series of short articles in "Nature," and forms one of the Messrs. Macmillan's "Nature Series." It is intended as a popular scientific rather than an exhaustive and technical account of its subject. The opening chapters deal with the general character and structure and the properties and varieties of timbers; also with the classification of timbers based on these properties. An extended review of the theories about the ascent of water in tall trees is given, the conclusion of the author being that of the imbibition theory of Sachs and the osmosis-gas-pressure theory of Hartig and Godlewski and others, the latter is the more probable. While he admits that the rhythmical character of the respiration of protoplasm, on which the osmosis-pressure theory depends, is not proved, he maintains that recent researches are in favor of Godlewski's views as to the behavior of the protoplasm. The next three chapters deal with the dry-rot and other diseases of timber caused by various fungi, figures of which are given. The structure of the bark of trees, and the process of healing wounds by occlusion, are then described, with illustrations. Returning to diseases, the author describes "canker," or the larch disease, leaf diseases, and pine blister. The final chapter deals with the "damping off" of seedling trees.

most conspicuous feature of this book is the thoroughness with which its contents has been analyzed, classified, and annotated. It is introduced by a chapter defining the field of economics and stating the nature of the chief schools of economists. The body of the work is divided into six parts, devoted respectively to production, exchange, money and credit, distribution, consumption, and "practical topics involving economic theory," which last includes chapters on coin and paper currency in the United States, taxation, and poverty. It is an elementary text-book, intended for classes in colleges and, with perhaps the omission of