436 Saturn's Ring. — Double Stars. — Occultations. 



ever, Arcturus will probably be generally owned as the leader 

 of the northern hemisphere : and in accordance with this, it 

 happened to be the first star seen by Morin, in 1635, in broad 

 daylight; as Morin was perhaps the first observer of stars 

 under such circumstances. Schmidt, formerly of Olmiitz, but 

 at present director of the observatory at Athens, has asserted 

 that Arcturus has changed its colour ; he had for 1 1 years con- 

 sidered it one of the reddest stars, and had, in 1841, compared 

 it with the planet Mars; but in 1852 he was surprised to find 

 it yellow, without a trace of red, and whiter even than Capella 

 to the naked eye. This alteration seems unconfirmed by his 

 contemporaries, but the subject is a curious one, as such a 

 change appears to be more than probable in the case of Sirius. 

 In another respect Arcturus is peculiarly interesting, as possess- 

 ing so great an amount of proper motion : its position alters 

 annually 2"'25 towards the S.W., so that supposing its rate to 

 have been invariable, it must have traversed a space equal to 

 about 7 diameters of the moon, since the creation of man. 

 This extraordinary displacement might be taken as an indica- 

 tion of comparative nearness to our system, and might be 

 wholly or in part ascribed to a contrary motion on the part of 

 our sun, did not the extreme minuteness of the parallax of 

 Arcturus (about 0"*169 according to Johnson) demonstrate its 

 astounding distance, requiring 19 years for the transmission of 

 its light to our eyes ; and prove at the same time its incalcu- 

 lable velocity and enormous magnitude. This is a golden sun 

 indeed — the centre, probably of a magnificent system of at- 

 tendant worlds. It is a grand object in the telescope, but 

 though we have deservedly given it some attention, it is but an 

 intruder in our list, and we proceed to 



19. e Bootis, 2"-9, 321°-2. 3 and 7. Pale orange and sea- 

 green. A pair well deserving of Struve' s epithet " pulcher- 

 rima," and long celebrated as a test of the goodness of 

 telescopes. The recent extension of their size and power now 

 demands a more rigorous criterion, but it is still very useful for 

 trying smaller instruments. An aperture of 2f inches ought 

 to bring it out ; I have seen it as a known object, but do not 

 suppose I should have discovered it, with 2i. W. Struve * 

 thinks there is no doubt of this pair being in slow motion, but 

 Smyth does not consider the question decided. This object is 

 closer than any that we have as yet attempted, and may be con- 

 sidered as our first introduction to a more difficult class, requir- 



* It has been recently announced that this distinguished observer, who ha9 

 rendered such eminent services to sidereal astronomy, has resigned the post of 

 President of the Imperial Observatory at Poulkowa, near St. Petersburg, Which 

 he has worthily filled for many years. He is succeeded by his son M. Otto 

 Struve. 



