Page:Popular Science Monthly Volume 60.djvu/289

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in the last issue of the 'Science Series' (Putnam), sums up our present knowledge of the stars. The greatest problem which can engage the human mind is the structure and duration of the Universe. This is the problem which the author proposes in the fourteenth chapter, and which he discusses throughout the rest of the volume. The early chapters may be regarded as forming an introduction to this far-reaching investigation. To present a popular statement of the facts of astronomy is no simple task. This the author keenly appreciates, for in the preface he admits that he has failed to satisfy himself. Nevertheless, no one could be better prepared to undertake the work than Professor Newcomb, and the outcome cannot fail to meet with general praise. The author possesses that rare style, which comes from a perfectly clear conception of the subject, and a good command of plain English. He can be exact without the use of technical language.

Among the important subjects, which are discussed in the volume, are the surveys of the stars, which are now in progress. These surveys are of different kinds. There are the cataloguing and numbering of the stars, which are still actively carried on, and by new and novel methods, due to the introduction of photography. To count and fix the positions of the stars is, however, not enough. There must also be photometric surveys, to determine the exact! brightness, and other surveys for the systematic study of the spectra, the parallax, and the motions of the stars. There must also be careful surveys of the nebulae. A most interesting investigation is that of the motion of stars in the line of sight, a study which has reached a wonderful precision at the Lick Observatory, with the great refractor and its spectroscope. This has thrown much light on the subject of double and variable stars. Other subjects of special interest are the great numbers of variable stars, which are found packed into a few dense clusters, and the life history and changes of a star. At present, owing to the incompleteness of the surveys and other studies no entirely satisfactory discussion of the structure of the Universe is possible. The subject, however, is treated in an extremely clear and interesting manner, and all the conclusions are drawn, in regard to the Universe, which the present state of the science permits.

book on Alaska has recently left the press of Doubleday, Page & Company (New York) in the form of a report on the Harriman Alaska Expedition of 1900. This expedition was organized by Mr. E. H. Harriman as a means of obtaining definite information concerning the characteristics and resources of the Alaskan coast and interior; and through the cooperation of the Washington Academy of Sciences a strong scientific character was impressed on the work. The personnel included a 'scientific party' of twenty-five specialists, several of them eminent in their respective lines; and every possible facility for original work was afforded these specialists in the course of the voyage and land journeys, so that important records and collections were obtained. The preparation of the material for publication was undertaken largely by members of the Washington Academy, and the papers