74 REPORT OF THE SECRETARY. 



determination of position of over 700 such absorption lines, and is one with which 

 the research, so far as it concerns only the discovery of new absorption lines, may 

 suitably close. 



The results we have already indicate the complete fulfillment of your expectation 

 that this great region is the chief seat of the telluric absorption, and confirm your 

 hopes that these researches may soon lead to knowledge of a character of perma- 

 nent utility to mankind. The gradual collection and improvement of apparatus 

 attending the prosecution of this investigation has placed the Observatory in a 

 condition to enter under highly favorable circumstances upon other researches 

 connected with radiant heat. 



Respectfully submitted. C. G. Abbot, 



Aid, acting in Charge, Astro-physical Observatory. 



Mr. S. P. Langley, 



Secretary of the Smithsonian Institution. 



