Page:Popular Science Monthly Volume 46.djvu/430

416 entered, and which was reached by railroad at only one point. The district has since developed into one of the most important iron-producing areas of the country. Before the beginning of the investigation, Prof. Irving had done a large amount of field work upon a portion of the range for the Wisconsin Geological Survey and had prepared a systematic report upon this part of it. He was thus able to direct the more detailed examination of the whole area, so that no loss of time should occur. This is the first of the iron-producing districts of Lake Superior in which the geology has been worked out in detail, and the fundamental conclusions reached are in opposition to those expressed by some geologists. Hence, in order to make the facts fully accessible to those who desire to have them, the descriptions of the formations and their sections are given with especial particularity. The first chapter of the present report was prepared by Prof. Irving; the third, fourth, and fifth chapters were jointly prepared; and the rest is the work of Mr. Van Hise.

work of the Geological Survey is the examination of the topography and the preparation of topographical maps showing the distribution and characteristics of the rock formations of the country with their various mineral contents. Usefulness in various other ways than for the geologist is justly claimed for the maps that result from the surveys—such as the location of roads, railways, and canals, for planning towns and extensive manufactories, for drainage and irrigation systems, and for all other works depending on the configuration of the ground. These uses are multiplying, as the resources and industries of the country are developed and increase, with every decade. The geological survey of each district requiring, by reason of the diversity of rocks and resources in the different parts of the country, special knowledge of that district, the work is organized in divisions, each assigned to a particular district or series of formations, in each of which are subdivisions in which work is carried on by independent parties; and there are other divisions of special kinds of work. The topographical surveys of Connecticut, Massachusetts, New Jersey, and Rhode Island are completed. The surreys of this branch during the year covered by the report serve to complete eighty-eight atlas sheets, of which thirty-six are on a scale of 1:62,500 (or about one mile to the inch), forty-five are twice as large, and seven are drawn to special scales. The general maps, it is claimed, are among the first to represent with approximate accuracy the relief of any considerable part of the country. A summary of the more important features of the surveys and the administrative reports of the chiefs of divisions, showing in general terms the amount of work done in each, are given in connection with the director's report.

In Part II, Geology (pp. 872, with numerous illustrations and maps, largely swelling the thickness of the volume), are given the full and detailed reports of the second expedition to Mount St. Elias, by I. C. Russell; The Mechanics of Appalachian Structure, by Bailey Willis; The Average Elevation of the United States, by Henry Gannett; The Rensselaer Grit Plateau of New York, by T. N. Dale; The American Tertiary Aphidæ, by S. H. Scudder.

Part III (486 pages, with illustrations and maps) relates to irrigation, and contains papers on Water Supply for Irrigation, by F. H. Newell; American Irrigation Engineering, by H. M. Wilson; Engineering Results of Irrigation Survey, by Mr. Wilson; a report upon the construction of topographic maps and the selection and survey of reservoir sites in the hydrographic basin of the Arkansas River, Colorado, by A. H. Thompson; and a report upon the location and survey of reservoir sites during the fiscal year ending June 30, 1892, by John Thompson.

one recalls the six or eight hundred octavo pages of most of the popular text-books on diseases of the throat, it seems that the author of this manual has