OF ARTS AND SCIENCES. 



413 



TABLE lY. — Continued. 



The light of the brightest stars is derived from Table V., as will 

 be described below. The letter a is substituted for the magnitude iu 

 the case of stars outside the limits of the photograph ; b is used to 

 designate stars in the central nebulosity, wliich are therefore not easily 

 distinguished ; c indicates stars visible on G, but not on F ; and d, 

 those not contained on either F or G. The sixth column gives the 

 magnitude derived from the photograph of Dr. Draper. The light of 

 each star in a copy of E was found by Argelander's method, and also 

 by arranging the stars in a sequence. The mean of these magnitudes 

 is that here employed. The last two columns give the residual, ex- 

 pressed in tenths of a magnitude, found by subtracting the Bond mag- 

 nitude from the photographic magnitudes given in the two previous 

 columns. 



A list of the stars visible in other copies of E is given by Professor 

 Holden in Table A, on page 228 of his Memoir. Three of these stars, 

 Nos. 685, 708, and 734, are too bright for satisfactory measurement in 

 E, and two others, 435 and 8G3, are not visible either in E, D, or C 

 No. 497 is apparently omitted by mistake in Professor Holden's list. 

 For five stars, 580, 650, 653, 063, and 709, the results derived from 

 E and F are discordant. The first three of these are the faintest 

 stars measured on E, and the last two are so surrounded by nebulo.sity 

 that the measure is difficult. Were the first three stars as faint as F 

 would indicate, it wouUl be impossible to see them on E. They are 

 certainly visible on D, and 653 on C also. No. 663 is brighter than 

 681 in E, as bright in D, and not seen in C; in F and G it is much 

 fainter than 681. 



