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no longer has command of language, in the light of which the organic conditions of learning to speak are considered, with important physiological results. The development of speech in the child during the first three years is described from observations on the author's own infant. The growth of the feeling of self, or the "I" feeling, is examined in a like manner; and the results are summarized, particularly as they bear upon the theory of the formation of concepts without language. In the appendixes are given "Comparative Observations concerning the Acquirement of Speech by German and Foreign Children"; "Notes concerning Lacking, Defective, and Arrested Mental Development in the First Years of Life"; and reports of several cases illustrating the process of learning to see, on the part of persons born blind, but acquiring sight through surgical treatment. A full conspectus, showing the results of Prof. Preyer's observations in a chronological order, arranged by months, is added by the translator, and very greatly augments the value of the book.

Popular Lectures and Addresses. By Sir William Thomson. In Three Volumes. Vol. I. Constitution of Matter. With Illustrations. London and New York: Macmillan & Co. Pp. 460. Price, $2.

The first lecture included in this volume deals with capillary attraction, explaining with the aid of diagrams the action of the forces which produce capillary phenomena. There are two lectures on electrical measurements: one describing how the units in present use have been arrived at and pointing out certain things in relation to them which should be advanced and perfected; the other dealing mainly with the construction of electrometers. The collection contains an extended discussion of the size of atoms, and an address entitled "Steps toward a Kinetic Theory of Matter." The most popular address in the volume is entitled "The Six Gateways of Knowledge, "and deals with the senses, including among them the temperature-sense. Prof. Thomson says there is no evidence for the existence of a magnetic sense. Another attractive paper to the general reader is a lecture on the wave theory of light, delivered in Philadelphia. There are two lectures on the sun's heat, one of which considers the probable limits to the periods of time past and future during which the sun can be reckoned on as a source of heat and light. The second volume of this series will include subjects connected with geology, and the third will be chiefly concerned with phenomena of the ocean and with maritime affairs.

Seventh Annual Report of the United States Geological Survey to the Secretary of the Interior—1885-'86. By J. W. Powell, Director. Washington: Government Printing-Office. Pp. 656, with Plates.

The report begins with an explanation of the purposes of the geographic division of the survey and the object of the topographic maps and methods of preparing them. In the geologic division the adoption of a scheme of taxonomic representation that shall be comprehensive and susceptible of extension as new features come to light is shown to be important. The perfection of the work of the survey has made necessary the establishment of accessory divisions of paleontology, chemistry, microscopic petrography, statistics and technology, forestry, and illustrations; and, in order that needed facilities may be provided for the consultation of the results obtained by other geologists, a library of 17,255 books, 19,600 pamphlets, and 9,000 maps, has been collected. Topographic surveys were carried on during the year over 81,829 square miles, at an average cost of about $2.75 per square mile. In the distribution of the work, the investigation of the archæan rocks has been conducted under the direction of Prof. Raphael Pumpelly; investigations of the Atlantic coast, including changes of level, by Prof. Shaler; in the Appalachian region, by Mr. G. K. Gilbert; in the Lake Superior region, by Prof. R. D. Irving; in Glacial Geology, by Prof. T. C. Chamberlin; in Montana, Yellowstone Park, Colorado, California, Volcanic Geology, the Lower Mississippi region (iron and other ores, sulphur and salt deposits, etc.), Potomac River and the head of Chesapeake Bay, by Dr. Hayden, Arnold Hague, S. F. Emmons, G. F. Becker, Captain Button, L. C Johnson, and W J McGee, respectively. In other branches of the studies, the surveys have been continued under the several specialists who have had them in charge in pre-