By Thomas C. Chamberlin and Rollin D. Salisbury, Professors in the University of Chicago. (American Science Series.) 2 vols. 8vo.

Vol. I. Geological Processes and their Results. xix + 654 pp. $4.00.

Vol. II. Earth History. [In preparation.]

This is a notable scientific work by two of the highest authorities on the subject in the United States, and yet written in a style so simple that it can be clearly understood by the intelligent reader who has had little previous training in the subject.

Chas. D. Walcott, Director of U. S. Geological Survey:—I am impressed with the admirable plan of the work and with the thorough manner in which geological principles and processes and their results have been presented. The text is written in an entertaining style and is supplemented by admirable illustrations, so that the student cannot fail to obtain a clear idea of the nature and work of geological agencies, of the present status of the science, and of the spirit which actuates the working geologist.

Henry S. Williams, Professor in Yale University.—I believe it is the best treatise on this part of the subject which we have seen in America.

R. S. Woodward, Professor in Columbia University:—It is admirable for its science, admirable for its literary perfection, and admirable for its unequalled illustrations.

T. C. Hopkins, Professor in Syracuse University:—It gives us the most advanced thought on all the great questions of dynamical and structural geology to be found in geological literature.

H. Foster Bain, U. S. Geological Survey:—The book is pre-eminently a teaching book and I have no doubt that it will at once become the standard American text-book on geology.

William N. Rice, Professor in Wesleyan University:—The book is full of new ideas. It is one of the indispensable books for the library of every working geologist and every one who wishes to be an up-to-date teacher of geology.

T. A. Jaggar, Jr., Assistant Professor in Harvard University:—The book appears to be an excellent statement of modern American geology, with abundant new illustrative material, based upon the most recent work of government and other surveys. It is especially satisfactory to have in hand a geological volume which does not attempt to cover the whole field. Modern geology is much too large a subject to be condensed into a single volume.