viii ADVERTISEMENT. 



for its examination. It is however impossible, in most cases, to verify the state- 

 ments of an author; and, therefore, neither the Commission nor the Institution can 

 be responsible for more than the general character of a memoir. 



The following rules have been adopted for the distribution of the quarto volumes 

 of the Smithsonian Contributions: 



1. They are to be presented to all learned societies which publish Transactions, 

 and give copies of these, in exchange, to the Institution. 



2. Also, to .all foreign libraries of the first class, provided they give in exchange 

 their catalogues or other publications, or an equivalent from their duplicate volumes. 



3. To all the colleges in actual operation in this country, provided they furnish, 

 in return, meteorological observations, catalogues of their libraries and of their 

 students, and all other publications issued by them relative to their organization 

 and history. 



4. To all States and Territories, provided there be given, in return, copies of all 

 documents published under their authority. 



5. To all incorporated public libraries in this countrj', not included in any of 

 the foregoing classes, now containing more than 10,000 volumes; and to smaller 

 libraries, where a whole State or large district would be otherwise unsupplied. 



