ADVERTISEMENT. 



The object of the General Appendix to the Annual Report of the 

 Smithsonian Institution is to furnish brief accounts of scientific dis- 

 covery in particular directions; reports of investigations made by 

 collaborators of the Institution; and memoirs of a general character 

 or on special topics that are of interest or value to the numerous 

 correspondents of the Institution. 



It has been a prominent object of the Board of Regents of the 

 Smithsonian Institution, from a very early date, to enrich the annual 

 report required of them by law with memoirs illustrating the more 

 remarkable and important developments in physical and biological 

 discovery, as well as showing the general character of the operations 

 of the Institution ; and this purpose has, during the greater part of 

 its historjr, been carried out largely by the publication of such papers 

 as would possess an interest to all attracted by scientific progress. 



In 1880 the Secretary 7 , induced in part by the discontinuance of an 

 annual summary of progress which for 30 years previous had been 

 issued by well-known private publishing firms, had prepared by com- 

 petent collaborators a series of abstracts, showing concisely the 

 prominent features of recent scientific progress in astronomy, geol- 

 ogy, meteorology, physics, chemistry, mineralogy, botany, zoology, 

 and anthropology. This latter plan was continued, though not alto- 

 gether satisfactorily, down to and including the year 1888. 



In the report for 1889 a return was made to the earlier method of 

 presenting a miscellaneous selection of papers (some of them origi- 

 nal) embracing a considerable range of scientific investigation and 

 discussion. This method has been continued in the present report 

 for 1917. 

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