Page:Popular Science Monthly Volume 54.djvu/729

Rh that, in spite of some difficulties, formal logic is one of the most valuable instruments in modern education for promoting clear thinking and for developing critical habits of mind. To doubters of the advisability of attempting to include a theory of thought or a philosophy of mind in an elementary course in logic, Professor Creighton replies that psychology having differentiated itself from philosophy and become a "natural" science, no longer undertakes to describe all that the mind is and does. "It belongs to logic to investigate intelligence as a knowing function, just as it is the task of ethics to deal with the practical or active mental faculties." Logic must first be a science before it can become an art, but it can not be regarded as an art in the sense that it furnishes a definite set of rules for thinking correctly. What it can do is to show the method by which new truths have been discovered and the general conditions that must always be fulfilled in reasoning correctly. The treatment in the text follows the usual order, except that the author, keeping clear of artificial diction, writes in talking English that is easy to be comprehended.

There are no more vital problems in the evolution of society than those connected with the point of view, the outlook, of the great masses of the "working people." These people form the backbone, the potential energy of society; an acquaintance with their views of ethics and life, and manner of living, is of the utmost importance, not only per se, but especially because of the efficient direction which such a knowledge can give the attempts at improving these latter, and through them society at large. Mr. Walter Wyckoff has, apparently actuated by some such view as this, in combination perhaps with a desire for a novel experience, made a two years' trip across the continent, living chiefly among the lowest and most improvident class of manual laborers; making his own living by their methods, and, by means of the close contact, studying them from a vantage point of unusual value. The account of this expedition is, as it could not fail to be, no matter who the traveler might have been, of great interest and value. But in Mr. Wyckoff's hands the story has an added attraction through the literary ability of the author. There is much material of practical scientific value in the volume; it should prove especially suggestive and useful to some of our charity organization workers who apparently find it so difficult to govern their work by reason rather than emotion. There are one or two rather unpleasant lapses, the most marked of which advertises in a Chicago police station Mr. Wyckoff's great linguistic attainments, but the work is generally free from this sort of weakness, and is on the whole very well worth reading for instruction as well as entertainment.

The Manual of Determinative Mineralogy of Professors George J. Brush and Samuel L. Penfield is intended primarily to be used in the identification of minerals, and that purpose has been kept prominently in view. The present edition is a complete revision of Professor Brush's original work, the value of which and the estimation in which it is held by its constituency are attested by the fact that fourteen editions of it have been issued since it first appeared in 1874. A revision of the parts devoted to blowpipe analysis and the chemical reactions of the elements was published in 1896. To the present edition a chapter is added on the physical properties of minerals, devoted chiefly to crystallography, in which the endeavor has been made to present the subject as simply as possible. Importance has been attached to the description of those forms which are of most frequent occurrence, and the examples chosen to illustrate the different systems represent, as a ride, the simple forms that prevail in specimens of common minerals, while rare and complex forms are treated very briefly. The introduction of a large number of species since 1874 has made a complete rearrangement necessary in the analytical tables; and they have been so developed that tests for characteristic chemical constituents furnish the chief means of identification. Stress is laid upon the importance