GREAT REFRACTING TELESCOPE AT ELCHIES, IN MORAYSHIRE. 393 



7 ANDROMEDA — continued. 



ponents. tude." Colour. Position. Distance. Date. Authority. 



A ... 



B ... AB 6217(^24) 10-552(w/24) 1830-76 Bessel. 



A 3-5 Orange 



B 5 5 Emerald green AB 61 36 (iw 9) 11-00 (w 9) 



C 5-5 Emerald green BC 120 (iw 1) 0-5 (m^ 1) 1843-33 Cycle. 



A ... Red orange 



B + C ... Lighter orange 1846-5 Sestini. 



~2~ 



A ... 



B ... AB 62 30 (w 9) 10-1 (m^ 9) 



C ... BC 115 0{wl) 0-5(wl) 1852-99 Spec. Hart. 



A ... Orange ^ 



B ... Green I 1856-68 AltaVista. 



C ... Green j 



A 2-0 



? t-? 5-4 A — ^ 63 23(m;36) 1860-90 I A. Auwers. 



10-270 (w 20) 1861-76 



A 3-5(1) Orange yellow (2)... 



B .5-5(1) Bluish green (2) AB6212(«;2) 9-8l(wOS)\ ^^ 



C 6-0(1) Bluish green(2) AC 116 23(w0-5) 0-58(wO-3)J ^"^^ '^ J^lctiies. 



In Magnitude, nearly steady. 



In Colour, A seems nearly steady ; but B, with or without C, rather variable 

 from blue to green at some periods, and purple at others. 



In Position and Distance, A and B nearly steady, B and C with symptoms 

 of orbital movement ; but as the tabular proper motion of A does not appear 

 between A and B, they may also be pronounced in character, slow binaries. 



The discovery of C, one of the many similar triumphs of the acute Otto 

 Struve, with the great Pulkova object-glass, is an admirable test of definition and 

 size of discs. My father's 5"9-inch object-glass would barely notch the B and C 

 pellet of light ; Mr Pattinson's 7" 25-inch on Teneriffe would separate the two 

 stars and show a dark line between, but still make the discs so large, that they 

 were mutually compressed on their adjacent sides, in order to allow the said 

 dark line to be formed: with the Elchies 11-inch however, the discs were so 

 much smaller that they were both completely separated and perfectly circular, 

 their diameters being, for B = 0"-3, nearly, 

 andforC = 0"-25, nearly. 



But there was this difference caused by the atmosphere of either locality, viz., 

 ' that at Elchies I only once, and then but for a short time, saw the stars thus 

 defined with all the power of the object-glass ; but at Alta Vista, on Teneriffe, I 

 saw them so night after night, and almost whenever I looked at them. 



