"28 REPORT OF THE SECRETARY. 



also received during' the past year, relating to subjects in physics and 

 chemistry. In accordance with the custom of the establishment, these 

 were submitted to gentlemen eminent in the several sciences to which 

 they pertained, who for many years have cheerfully acted as collabora- 

 tors of the Institution. 



Although the Smithsonian system of meteorology was several years 

 ago transferred to the United States Signal Office, communications con- 

 tinue to be received on practical questions connected with this subject. 

 These with few exceptions have been referred to General Myer, and their 

 authors so informed. 



But increase in the correspondence of the Institution is by no means 

 wholly attributable to the sources above mentioned. As the character 

 of the establishment has become more widely known from year to year, 

 the number of applications for information in the line of natural history 

 has annually increased, particularly in botany, zoology, and mineralogy. 

 In the last branch, supposed discoveries of mineral wealth are frequently 

 made known to the Institution, and the specimens forwarded for exani- 

 baation — which is always gratuitous. The determination of their char- 

 acter, however, seldom requires more than a qualitative analysis, and 

 in the great majority of instances the specimens are found to be of. no 

 commercial value. 



EXCHANGES. 



There is, perhaps, no one feature of the Smithsonian Institution by 

 which its mission for the diffusion of knowledge, if not its increase, is 

 more thoroughly accomplished than by its extended system of interna- 

 tional exchanges. This began in the earliest days of the Institution, from 

 the necessity of making some suitable arrangement by which its publi- 

 cations might be promptly transmitted to the learned societies of Amer- 

 ica and the world, and corresponding works received in return. This 

 required the organization of a thorough system, including special ar- 

 rangements for transportation agencies in the various parts of the United 

 States and of foreign countries ; and as the machinery was sufficient to 

 carry a larger amount of material than that belonging to the Institution 

 itself, it was considered iu strict accordance with the policy of the In- 

 stitution to offer its services to other establishments. 



Year by year the number of participators in the exchange was in- 

 creased, and at the present date it is world-wide in its extent. With 

 very few exceptions the institutions of learning, not only of the United 

 States but of all America, carry on the greater portion of their scientific 

 exchanges with the rest of the world through the Smithsonian Institu- 

 tion. Among the outside countries more especially to be mentioned 

 are Canada, Mexico, Chile, Venezuela, &c. 



The institutions are for the most part scientific societies publishing 

 transactions, colleges and universities, State historical and agricultural 

 societies, and technological institutions. All the departments of gov- 

 ernment in Washington, with few exceptions, also depend upon the same 



