ANNALS OF THE ACADEMY 7 1 



trum, and was presented at a public session held in the National 

 Museum on the evening of April i6. The President, in a 

 presentation address, mentioned the following memoirs as being 

 those for which, in particular, the award was made: A mathe- 

 matical paper on the Theory of Concave Diffraction Gratings; 

 a memoir upon the Practical Construction of a Screw of a Linear 

 Dividing-Engine; a Research upon the Solar Spectrum, "in- 

 cluding the magnificent charts which accompanied it, produced 

 by photography " ; investigation upon the Absolute Wave- 

 Lengths of the Lines in the Solar Spectrum; investigations upon 

 the Spectra of the Elements, and particularly of the Spectra of 

 Iron and Carbon. 



In November of the same year the third Watson Medal was 

 awarded to Dr. Arthur Auwers, of Berlin, " for his contribu- 

 tions to stellar astronomy, including his superintendency of the 

 zone observations of the Astronomische Gesellschaft, his re- 

 searches on variable proper motions, and his re-discussion of 

 Bradley's observations." The award was made effective in April, 

 1891, when the medal and one hundred dollars in gold were 

 transmitted to Dr. Auwers through the German Embassy in 

 Washington. In reporting on the award, the committee made 

 special reference to Dr. Auwer's investigations of the proper 

 motion of Sirius and Procyon, his determination of a fundamental 

 system of declinations to which all catalogues of stars should be 

 reduced, his work on the parallaxes of the fixed stars, and also to 

 his new reduction of Bradley's epoch — making observations, 

 which was characterized as his greatest work. 



President F. A. P. Barnard, of Columbia College, one of 

 the incorporators of the Academy, who died on April 27, 1889, 

 provided in his will for a gold medal which should be awarded 

 every five years to the person making " such discovery in physi- 

 cal or astronomical science, or such novel application of science 

 to purposes beneficial to the human race, as, in the judgment of 

 the National Academy of Sciences of the United States shall be 

 esteemed most worthy of such honor." This medal, which was to 

 be styled " The Barnard Medal for Meritorious Services to 



