ADVERTISEMENT. 
The object of the Genrrat Arrrenpix 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. 
Tt 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 history, 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, 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 1919. 
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