ANNALS OF THE ACADEMY Wal 
trum, and was presented at a public session held in the National 
Museum on the evening of April 16. 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 
