PREFACE. 



The present volume of the " Annual Record of Science 

 and Industry " constitutes the sixth of the series, and is in- 

 tended to present an intelligible and popular account of 

 the more important facts of progress in the various depart- 

 ments of the physical and natural sciences, and their ap- 

 plications to the conveniences and luxuries of mankind. 



Its distinguishing features, as compared with other 

 works intended to answer the same general purpose, are 

 as follows: 



First, a series of summaries of progress in the different 

 branches of physical, natural, and industrial science, pre- 

 pared by a number of the most eminent specialists in the 

 United States, whose collaboration the editor has been so 

 fortunate as to secure. 



Second, a series of abstracts, more or less systematically 

 arranged, of special papers, memoirs, or other publications, 

 by various writers, and with references to the title, volume, 

 and page of the source of information ; these abstracts 

 very rarely being transcripts from the original, but digests 

 in which only the points of special novelty and interest 

 are presented, with omission of irrelevant matter, and not 

 unfrequently with critical remarks and elucidations. These 

 have been for the most part edited and prepared by the 

 specialists referred to. 



Third, a list of the losses in scientific circles by death 

 during the year. 



Fourth, a list of the more important publications in 

 science for the year embraced within the scope of the 

 Record^ with references to ci'itical notices, serving as a 

 guide to students and purchasers of books. In connection 



