OF ARTS AND SCIENCES. 



269 



TABLE X. — Variation in Light of 8 Ckpiiei. 



These residuals are not large, considering the differences between the 

 different observed values. There is, however, a curious alternation 

 of the positive and negative signs. As a similar alternation appears 

 in some of the other residuals, it is important to compare them to see 

 if they can be shown to follow any law. There appear to be three 

 maxima and three minima, or the variation repeats itself at intervals of 

 about 120°. "We should then exaggerate this effect by adding each 

 set of the three residuals differing by 120° ; that is, the residuals cor- 

 responding to 0°, 120°, and 240°, to 15°, 135°, and 255°, etc. This 

 is done in Table XI., in which the first value of v, in each set, is 

 given in the first column, and the suras of the three residuals for 

 the four stars are given in the second, third, seventh, and eleventh 

 columns. The residuals of I Geminorum are so small that we should 

 expect no evidence of systematic error. In the other three cases 

 marked variations are shown. In each case there are only two 

 changes of sign, while there should be on the average four if the vari- 

 ations were accidental. The residuals oi jB Lyrce are well represented 

 by subtracting from the computed value 3 cos 3 v. The residuals 

 which then remain are given in columns four, five, and six. Their 

 average value is l.G instead of 2.8, or they have been reduced nearly 

 one half. The residuals of rj AquilcB, in like manner, leave 1.1 instead 



