Page:Popular Science Monthly Volume 51.djvu/140

132 From some passages in their writings it would seem that each of these worthies came within a step or two of discovering all the main facts relating to the composition of the air, but each failed to look quite far enough in the right direction. Boyle, it appears, reasoned shrewdly from imperfect observations; Mayow died young; while Hales accumulated many and definite experimental facts, but lacked the ability to make use of them. All were hampered by the current errors of their time, among which the chief were the inability to distinguish one gas from another, lack of attention to gain or loss of weight, and above all erroneous ideas regarding combustion. Prof. Ramsay shows how the phlogistic theory, which came up about the end of Boyle's life, interfered with the researches of his successors—Black, Rutherford, Priestley, and Cavendish—until it was overthrown by Lavoisier. We are told something about the achievements of each of these men, and the account is made more interesting by including descriptions and portraits of the men themselves. After Cavendish little apparently remained to be done but to make more exact determinations of the constituents that had been found in the air. But in the course of some investigations in 1892 Lord Ray leigh noticed that nitrogen prepared from ammonia is somewhat lighter than atmospheric nitrogen. A research undertaken to find the reason for this difference brought out the existence of the inert argon. The circumstances of the discovery and the reasoning which led to it are set forth by Prof. Ramsay, who adds chapters giving the properties of argon and its position among the elements. The author has succeeded well in keeping his book within the comprehension of the persons without special scientific training for whom it was written.

Prof. Crockett's Elements of Plane and Spherical Trigonometry, by a mathematician of note who is Professor of Mathematics and Astronomy in the Rensselaer Polytechnic Institute, has been prepared for the use of beginners in the study. Assuming that a high degree of proficiency can not be expected from such students, the author, not striving after original demonstrations, has limited himself to the selection of simple proofs of the formulas, to which geometrical proofs have in many cases been added. The definitions and explanations are admirably clear and concise. The numerical examples have been computed by the author, with special attention to correctness in the last decimal place. The tables are a special feature, are printed from differentiated type, and on paper of a different tint from the text, so as to make them easier to turn to. They give five places, while the angles in the examples are given to the nearest tenth of a minute. We find the book lucid and convenient.

The recent book of Prof. Keasbey on the Nicaragua Canal urges frankly and emphatically the choice of the Nicaragua route for a canal across Central America, and the assumption by the United States of a dominant position in the political control of this water way. The author opens his discussion with a brief description and comparison of the ten or twelve more or less distinct routes that have been proposed, expressing the decided conviction that the Nicaragua and Panama routes are the only two worth considering, with the advantage on the side of the former. The greater part of the volume is devoted to a history of the attempts that have been made to construct canals in this region and to obtain political control of the territory through which they would pass. The record begins with the first Spanish explorations, and mentions canal projects of Spanish engineers formed before 1550. A chapter on the English freebooters opens an account of the struggle between England and Spain, lasting into the early part of the present century. The term from 1815 to 1865 Prof. Keasbey characterizes as a period of private initiative in canal projects. Two events in this division of his record which have an important bearing on the idea of cutting the American isthmus are the enunciation of the Monroe doctrine and the execution of the Clayton-Bulwer treaty. The time since 1865 he describes as a period of governmental activity in this matter, and he closes his chronicle of recent events by giving his view of the