Entered according to Act of Congress, in the year 1876, by In the Office of the Librarian of Congress, at Washington. PREFACE. In presenting to the public the fifth volume of the series of the "Annual Record of Science and Industry," a few words in explanation appear to be called for. In each of the successive numbers already published, new features have been introduced, suggested by experience as well as by the advice of the scientific collaborators and friends of the editor.* These are exemplified in part by the increasing number of communications and criticisms on progress in the various branches of science, and by the greater extent of historical résumés given under the caption of "General Summary of Progress.' These have gradually increased in the successive years from 16 pages in the volume for 1871, to 272 in that herewith presented. The editor has been pleased to notice that his endeavors thus to increase the value of the work have been on the whole cordially appreciated by the public at large. With much of praise, however, sundry friendly suggestions for modifications and improvements have been made which merit attention. It has been urged, on the one hand, that some new facts and memoirs deserving of attention have not been referred to; on the other, that the preliminary * Among those who have taken part in the preparation of the historical Summaries, or of abstracts of articles belonging to their respective specialties, or who have supplied early reports of their own original researches, may be mentioned: Professors Simon Newcomb, Cleveland Abbe, Edward S. Holden, Theodore Gill, and O. T. Mason, of Washington; Professors G. F. Barker, E. D. Cope, and Dr. William Wabl, of Philadelphia; Professor C. F. Himes, of Carlisle, Pa.; Dr. Charles Rau, of New York; Dr. E. S. Dana, of New Haven; Professor W. O. Atwater, of Middletown, Conn.; Dr. T. Sterry Hunt, of Boston; Dr. A. S. Packard, Jr., of Salem; Professor Asa Gray and Dr. W. G. Farlow, of Cambridge; Professor Hamilton L. Smith, of Geneva, N. Y.; Professor F. W. Clarke, of Cincinnati; Prof. A. W. Bennett, of London, and other gentlemen who prefer to remain unnamed. |