OF ARTS AND SCIENCES. 



265 



TABLE V. — Comparison Staus rou fi Ltr^. 



Tlie estimate of e Lyrce has not been included in drawing these 

 curves. As the observations were made with tlie naked eye, in sonae 

 cases aided by an opera-glass, e and 5 LyrcB were treated as a single 

 star. Wolff gives the logarithms of their light as 8.50 and 8.45. 

 Their combined light would therefore equal 8.77, or nearly half a 

 inajrnitude brighter than would be inferred from the estimate in 

 grades, using the curves derived from the other stars. This may also 

 be expressed by the statement that, together, they appear only a 

 quarter of a magnitude brighter than either would alone, while a star 

 of their combined brightness should appear about three quarters of a 

 magnitude brighter than the separate components. It is possible that 

 their proximity affected their measures by Wolff, but this seems less 

 probable since they would be readily separated by the telescope of a 

 ZoUner photometer. Evidently, c Lyrce should not be used hereafter 

 as a comparison star for this variable. 



Table VI., like Table III., serves to compare the observations with 

 theory. The first column gives the angle ; the second, the correspond- 

 ing time. Three sets of three columns each give the light in grades, 

 in logarithms, and in percentages, for Argelander, Oudemans, and 

 Schonfeld. Although the observations are not of equal value, it would 

 be difficult to decide what weight should be given to each, and espe- 

 cially, to decide how large are the systematic errors to which each is sub- 

 ject. This last quantity should determine the weight, since the accidental 

 errors are in a great measure eliminated by the smoothness of the light 

 curves. Their mean, which is given in the next column, will accord- 

 ingly be employed. The excess of the curve of each observer over 

 the mean is given in the next three columns. An examination of the 

 mean curve shows that it has two equal maxima symmetrically situated 

 on each side of the point where v = 180°. The curve must there- 

 fore have the form L ^ a -{- m sin (v — 90°) -j- n sin (2 v — 90°). 



