REPORT OF THE SECRETARY. 7 



I have continued to give what time and thought I can to investiga- 

 tions in astro-physics, which arc so extensive and, I hope, so important, 

 as to justify a considerable separate mention under the title, Astro- 

 physical Observatory, in the Appendix of this report. 



In what I have said I have principally referred to research in the 

 physical sciences, since aid to original research in the biological sci- 

 ences has been largely, though indirectly, provided through the 

 Institution's connection with the National Museum and otherwise. It 

 would, therefore, seem proper that what aid to scientific men can be 

 given from the original Smithsonian fund should be principally devoted 

 to the physical sciences, which are not otherwise cared for. 



As iu previous years, aid to a limited extent has been given to 

 original investigators who are not immediately connected with the 

 Institution. Prof. E. W. Morley has continued his determinations of 

 the density of oxygen and hydrogen, for which special apparatus has 

 been provided by the Institution, 



A paper by Prof. A. A. Michelson, upon the ''Application of interfer- 

 ence methods to spectroscopic measurements," with a view to increased 

 precision in measuring specific wave-lengths of light, has been published 

 in connection with his work upon a universal standard of length. Mr. 

 F. L. O. Wadsworth was detached from the Observatory staff, and sent 

 (at the expense of the Smithsonian fund) to the Bureau Internationale 

 des Poids et Mesures near Paris to assist Prof. Michelson during a stay 

 of six weeks iu the preparation of this standard. 



Prof. Holden, the director of the Lick Observatory, Mount Hamilton, 

 Cal., is still engaged in lunar photography, for which some occasional 

 aid has been given in j)revious years by the Institution. 



The subscription for twenty copies of the Astronomical Journal, 

 which are distributed abroad as exchauges of the Institution, has 

 been continued. 



In the Astro-physical Observatory the investigations of radiant 

 energy alluded to in my i^revious reports have been continued, and 

 very interesting results have been obtained. I have referred, on 

 another page, somewhat at length to the work of the Observatory, 

 and further details are contained in the report in the Appendix. 



The Hodgkins researches have already promised to assume such 

 importance that they have also been given a special i)lace upon a 

 later page of the present report. 



EXPLORATIONS. 



I am much gratified to report the safe return of Mr. W. W. Rockhill 

 from his dangerous journey in Tibet. His explorations have added 

 much to our knowledge of these regions, and a portion of the collection 

 he has made will eventually be placed in the National Museum. Mr. 

 Rockhill is now engaged upon the preparation of a special report of 



