Page:Popular Science Monthly Volume 27.djvu/728

708 field; to explain the methods of field-work so clearly and minutely that an engineer in practice could, without other instruction, prepare his instruments, and do the work in good shape; and to furnish means of reducing the field-notes and methods of plotting, the results of many years' experience of many engineers.

is devoted to the study of the history and civilization of the aborigines of the Americas, and pursues it with industry in all its branches. In the present monograph he gives the results of his analyses of the words for weights and measures in the Maya, Cakchiquel, and Nahuatl or Aztec languages, instituted to ascertain, if possible, what units, if any, were employed by the peoples who spoke them. The measures of these nations seem to have been derived from the body, and some of them were curious. A unit of land-measure among the Cakchiquels was the circumference of the human figure. A man stood erect, his feet together, and both arms extended. The end of a rope was placed under his feet and its slack placed over one hand, then on top of his head, then over the other hand, and was finally brought to touch the beginning. This gave somewhat less than three times the height. The Aztecs had four measures from the point of the elbow: one to the wrist of the same arm, a second to the wrist of the opposite arm, a third to the ends of the fingers of the same arm, and the fourth to the ends of the fingers of the opposite arm. Neither of the three nations was acquainted with a system of estimation by weight, or with the use of the plumbline, nor with an accurate measure of long distances.

volume is the seventeenth of the series of "Naval Professional Papers." Its purpose is to exhibit in a concise form the principal phenomena of the deviations of the compass on iron ships. First are described the characteristics of a steel magnet, the method of determining those characteristics for any particular one, and the reciprocal action of two magnets. Next, the similitude of the magnetism in an iron or steel ship to that of an ordinary bar magnet is established, and the inquiry is made applicable to the ship, whereby we may become acquainted with her magnetic peculiarities. These observations are complemented by a number of experiments, all helping to complete the investigation, and to bring out a more satisfactory elucidation of the subject.

purpose and character of this elaborate volume are admirably summed up in its comprehensive title-page. The author has taken to metaphysics from the most modern point of view, and labored with great assiduity, much learning, and no little analytic and constructive skill, to work out the grand conception of unity in the world of philosophical thought. Firmly accepting that important principle of science, that the fewer assumptions we make in the explanation of things the better, he has labored to reduce the number of principles hitherto postulated as the primary elements of existence, and to show that there is but one final and universal principle, of which all others are but derivative expressions. Part I, consisting of eight chapters, is an epitome of the history of philosophy from the dawn of speculation among the Greeks down to the eclecticism and positive philosophy of France and the Scotch school. The contributions of the most illustrious philosophers embraced in that long period are sifted and estimated with a view to their bearings upon the fundamental proposition which the author finds himself called upon to establish. Part II consists of eight chapters, devoted to "The Nature of Perception," four of which are given to Herbert Spencer and four to G. H.