The primary objects of Mr. _Hoffman's The Sphere of Science_[16] are to point out what constitutes a science, and set forth the ground upon which every science rests and the principles and rules that must be followed in order to construct one. The author maintains throughout that every department of knowledge is capable of scientific treatment, and must be so treated before any great advance can be made toward a consistent and rational conception of the universe. The subjects are considered in succession of the true conception and aims of science, what it takes for granted, the scientific method, certainty and probability in science, the use of the imagination, analogy as an aid, the limitations of science, recent advances in the physical sciences, the old and new psychology, modern scientific ethics, philosophy as the science of the sciences, and the harmony of the sciences. The author holds that the chief need in all departments of thought is not so much mere facts as a new arrangement and classification of facts already at hand; that we can be certain of no doctrine, but the most we can do to establish it is to show that the balance of probabilities is in favor of it; that philosophy is the life of science and science the vital breath of philosophy, and if one is severed from the other both pine away and die; and that those scientific researches are successful which are not exclusively special, but are illuminated by an ample idea of science. The book is the outcome of a series of lectures given to classes in Union College to supplement their work in formal logic. * * * * * The _Text-Book of Geodetic Astronomy_[17] was prepared by Mr. _John F. Hayford_ to meet the conditions of the course at Cornell University, the terms of which the standard works now in use could not be made to fit. The purpose of the book is to furnish a text short and easy enough to be mastered by the student of civil engineering in a single college term which shall give him a sufficiently exact and extensive knowledge of geodetic astronomy to serve as a basis for practice in that line after graduation. While it is primarily a manual for students, the author has endeavored to insert such matter, tables, and convenient formulas as would make it of value also to the engineer making astronomical observations. Mathematical processes have been omitted, except those that are actually necessary for developing the working formulas, and simple and special means for deriving the formulas have been chosen in every case admitting choice. Considerable attention has been devoted to a discussion of the various sources of error in each kind of observations. Those formulas have been selected, so far as possible, that lead to accurate and rapid computation. * * * * *