OF ARTS AND SCIENCES. 



387 



TABLE IX. — Rate of Change in Light. 



The greatest chancfe in lio-ht amounts to two hundredths of a maff- 

 nitude a minute, or at the rate of a magnitude and two tenths an hour. 

 This is much greater than the change of any other known variable, 

 being over three times that of /3 Persei. Accordingly, we should expect 

 a corresponding increase in the accuracy with which the time of min- 

 ima could be determined. 



The observations of DM, 81°25 are grouped in Table X. The suc- 

 cessive columns, like those of Table IV., give a current number, the 

 condition limiting the group, the number of sets, the arithmetical sura 

 of the residuals, their algebraic sum giving to each the sign of B divided 

 by a, and the correction to be inferred, or AR divided by 2«. The 

 remaining columns give the probable error, the average of the resid- 

 uals, and the average difference of the three sets of four contained in 

 each set of twelve settings. 



TABLE X. — Comparison of Results. 



