Page:Popular Science Monthly Volume 54.djvu/291

Rh their study by transmitted light. There are three cuttings from each species, transverse, radial, and tangential to the grain. An accompanying text gives a condensed description of each tree, including its physical properties, uses, and habitat. These descriptions are preceded by a useful introduction to the study of general botany, describing the methods of distinguishing and naming the various parts of plants and trees, and giving an account of their structure and methods of growth. The actual wood sections, quite apart from their scientific value, are worthy of attention because of their great beauty. They are substantially mounted on black cardboard, each card containing the three sections of a species, and its common name in English, French, German, and Spanish. The thinness of the cuttings makes it possible to use them as transparencies, thus bringing out the texture of the wood in a very effective way.

Prof. Charles Reid Barnes is impressed with the fact that while laboratory work has become nearly universal in botany, and laboratory manuals are numerous, there is still a lack of books giving an elementary account of the form and functions of plants of all groups. To supply this want he offers Plant Life as an attempt to exhibit the variety and progressive complexity of the vegetative body; to discuss the more important functions; to explain the unity of plan in both the structure and action of the reproductive organs; and to give an outline of the more striking ways in which plants adapt themselves to the world about them. He has made the effort to treat these subjects so that, however much the student may still have to learn, he will have little to unlearn. The book is not intended to be memorized and recited, but to be intelligible to pupils from thirteen to eighteen years of age who are engaged in genuine laboratory study under the direction "of a live teacher who has studied far more botany than he is trying to teach." It is adapted to use supplementarily to any laboratory guide or to the directions prepared by the teacher. The directions are made fullest in relation to cryptogams and physiology, because these fields are at present most unfamiliar to teachers.

Attaching great importance to Electro-Dynamics, which he thinks will in the near future assume the same relation to the electric motor that the science of thermo-dynamics already bears to the steam engine, Mr. Charles Ashley Carus-Wilson aims in the book of that name to apply the principles of that science to the direct-current motor. Writing for electrical engineers particularly, he takes for granted a certain acquaintance with the use and design of motors, but avoids unexplained technicalities as far as possible. He has not deemed it necessary to deal with self-induction, except in connection with the question of sparking. The numerical accuracy attempted has been limited to that attainable with an ordinary ten-inch slide rule, on which all the examples have been worked out. Importance is attached to the graphic method of solution.

Of Dr. Frank Overton's three books on Applied Physiology, the first or primary grade follows a natural order of treatment, presenting in each subject elementary anatomical facts in a manner that impresses function rather than form, and from the form described derives the function. The facts and principles are then 'applied to everyday life. The intermediate grade, besides being an introduction to the study of anatomy and physiology, is intended to be a complete elementary book in itself, giving a clear picture of how each organ of the body performs its work. The advanced grade book was suggested by a series of popular lectures in which the author presented the essential principles of physiology about which a physician is consulted daily. His explanations of many common facts were "novel to his auditors, and it was found that the school books were silent upon many of these points, especially with regard to the cells. Throughout the series the fact that