Entered according to Act of Congress, in the year 1872, by

HARPER & BROTHERS,

In the Office of the Librarian of Congress, at Washington.

PREFACE.

THE design of the present work is to furnish a brief, yet sufficiently full, mention of the more important discoveries in the various departments of science during the year 1871, selecting, however, only such as appear likely to excite a general interest, or to be of lasting importance. The special student of Astronomy, of Chemistry, or of the physical sciences generally, of Natural History in any of its branches, etc., will, of course, not confine himself to the brief abstracts of a work like this. Such persons can only be satisfied with the publications devoted particularly to their several chosen departments of science, in the pages of which they may hope to be enabled to pursue their studies and investigations through all the minutest details of progress,

The very complete series of publications of learned societies, and of journals specially devoted to various branches of science, belonging to the Smithsonian Institution, have been kindly placed at the service of the editor by its Secretary. With the facilities thus furnished for surveying the field of science, with the aid, in addition, of numerous foreign and domestic scientific serials received by mail for use in this connection (enumerated at the end of the volume), the editor trusts that not much of a general interest or importance has been overlooked.

In providing for the general public, there is, of course, a great margin for varying tastes and judgment, and no two minds would probably agree exactly as to what should be selected and what omitted. In making his choice, the editor has endeavored to do proper justice to all the various subjects of scientific interest and research, and to neglect nothing of real interest, and he has endeavored not to allow his own partialities to influence him unduly in his se