256 



PROCEEDINGS OP THE AMERICAN ACADEMY 



TABLE Yll.— Continued, 

 a ScoEPii. 



The measures of the different photographs of the first four stars agree 

 as well as could be anticipated. The accidental errors are small consider- 

 ing the extreme faintness of many of the images. No large systematic 

 deviations appear, except in the case of a Li/rce, Plate 73, to which ref- 

 erence has already been made (p. 253). Small systematic errors are, 

 however, perceptible in other plates, as in No. 34, where the residuals 

 change from positive to negative, and in No. 45, where they change from 

 negative to positive. They will not, however, sensibly affect the final 

 result, and scarcely justify the application of a separate correction. 



A comparison of the lines in a AquilcB * and a Li/rce is given in 



* A peculiarity of the spectrum .of a Aquiiaa deserves special mention. 

 Besides tiie intense broad hydrofren bands whicli cliaractcrize the spectrum of 

 o Lyroe and similar stars, it exhibits a niullitudo of very fine lines, whicli are 

 easily seen between 6 and II in several of the plates, but are too delicate to be 

 satisfactorily measured. Dr. Draper considered these fine lines very important, 

 as showing that tiiis star — Altair — should be considered a sort of intermediate 

 link between a Lyras and Sirius on one side, and CapcUa and the Sun on the 

 other. — C. A. Y. 



