PREFACE. 



In presenting to the public the fifth volume of the se- 

 ries 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 expe- 

 rience as well as by the advice of the scientific collabora- 

 tors 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 resumes 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. Hol- 

 den, Theodore Gill, and O. T. Mason, of Washington ; Professors G. E. 

 Barker, E. D. Cope, and Dr. William Wahl, of Philadelphia ; Professor C. 

 E. 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 E. W. Clarke, of Cincinnati ; Prof. A. W. Ben- 

 nett, of London, and other gentlemen who prefer to remain unnamed. 



