State so far as determined during the two years' existence of the survey. In the course of the second year the co-operation of the United States Geological Survey and of the United States Coast and Geodetic Survey were secured in topographical work, much to the advantage of all branches of the work of the State Survey. Several geologists worked during the year at mapping the iron ores of the east Texas district, and the associated clays and lignites were also studied. Prof. Robert T. Hill studied the economic geology of the Cretaceous area, but resigned from the survey without making his report. Prof. W. F. Cummins was engaged in a detailed study of the coal measures of the central coal field; the Guadalupe Mountains were explored by Mr, Tarr; and further work on the mineral resources of central Texas was done by Dr. T. B. Comstock, who discovered tin in this region and obtained much information concerning the deposits of other metals, and of granite and salt. In the trans-Pecos region. Prof. W. H. Streeruwitz, after completing the topographic mapping of an important area, spent the rest of the season in examining the mineral veins of the region. For lack of books and type specimens most of the paleontological work on the Texas rocks has been done outside the State. An offer by the State Geologist to furnish collections of the rocks and minerals of Texas to the high schools of the State brought more applications than could be filled; forty-one sets, more or less complete, were furnished. The details of the year's work are given in the papers accompanying the report of Prof. Dumble, the text being illustrated with maps of the several localities, drawings of sections, and photographic views.
An Introduction to the Mathematical Theory of Electricity and Magnetism. By W. T. A. Emtage. New York: Macmillan & Co, Pp. 228. Price, $1.90.
This work, which appears in the Clarendon Press Series, is adapted to students far enough advanced to possess a knowledge of differential and integral calculus. It is complete in itself, and may be read without previous knowledge of the subject. Purely experimental parts of the subject requiring no special mathematical treatment have been entirely omitted.
Plane and Solid Geometry. By Seth T. Stewart. New York: American Book Company, Pp. 406. Price, $1.12.
Prominent features of this text-book are its strict adherence to the principle of association and its graded exercises. Each book treats of one subject, and each section treats of one subdivision of the subject, so that all relating to the subject or its subdivisions being placed together, the several parts will support one another in memory by the law of association. The same method of arrangement—the resultant form of the book being one that is rendered possible only by the grouping of propositions—favors the regular gradation of exercises. At the end of each section miscellaneous exercises, assorted and graded, are presented in an order intended to promote, by their successive solution, a constant growth in the power of analytic and synthetic thought. A synopsis of each book precedes the book itself, as an encouragement to students to work independently of the demonstrations given in the text. Thus, before giving the definitions of points, lines, and angles, the pupil is set to construct them if we may use the word, after which the definition follows, of necessity; and so on, through the book. The inductive method is in this way employed in the treatment of each part of the work; but, while the approaches to the subject are thereby rendered more agreeable, the author has been conservative in retaining, as far as possible, the usual phraseology of propositions and a wholesome rigor in demonstration. Throughout the volume the diagrams and demonstrations are in full view of each other.
No. 3, Vol. IV, of The Journal of Morphology, contains seven papers. The first embodies some Studies on Cephalopods, in regard to Cleavage of the Ovum, by S. Watase. It is illustrated with four plates and nineteen figures in the text. J. Playfair McMurrich has a second installment of his Contributions on the Morphology of the Actinozoa in this number, dealing with the Development of the Hexactiniae, It is accompanied by a plate. There are short papers by G. Baur on Intercalation of Vertebreæ, and by W. M. Wheeler on Neuroblasts in the Arthropod Embryo. G. Baur also contributes a paper on The Pelvis of
