274 WorJcfor the Telescope. 



Alcor is of tlie fifth magnitude, and is distant 11' 30" from 

 Mizar. It is known as the " rider upon the horse ;" the middle 

 one of the team of three, in the figure of Charles's Wain, as 

 Ursa Major has been popularly called in this country. This 

 name must be very ancient, long before Shakespeare's time, for 

 we find from Admiral Smyth that it is familiarized from the 

 Gothic Karlwagen, the charl (ceorl, Saxon) or peasant's cart. 

 Alcor seems to have formed a trial of sight among the Arabians, 

 according to their proverb, u Thou canst see Alcor, yet canst 

 not perceive the full moon;" they gave it also the name of 

 Saidak, the " test" ; and hence Arago thinks a change may be 

 inferred, as it is now so readily visible : it was also known 

 amongst them, as the Admiral tells us, by the term Suha, and 

 implored to guard its viewers against scorpions and snakes; 

 why, it does not appear. 



Mizar seems to have been a strange stumbling-block to 

 observers in the last century ; and for no intelligible reason, as 

 it is so easy an object. Its duplicity was discovered by Biccioli, 

 nearly in the middle of the seventeenth century : it was again 

 noticed in 1 700 by Gottfried Kirch and his scientific wife, Maria 

 Margareta, who was subsequently, in her widowhood, astronomer 

 to the Academy of Sciences at Berlin : and it was observed 

 double by Bradley in 1755 : yet Flaugergues used to try his 

 telescopes upon it aboiit and after the year 1750, without per- 

 ceiving the companion till 1787 : and even then he fancied that 

 the pair gradually widened to three or four times its original 

 distance ; which, as Smyth remarks, ' ' must have been merely 

 the effect of becoming better acquainted with the object before 

 him." Even such men as Delambre and Mechain have been 

 suspected of overlooking the smaller star : and there is a strange 

 story told about Madler at Dorpat as recently as 1841, when, 

 on observing this star by day, he was astonished to find it 

 single; he waited till after sunset in vain, perceiving in the 

 meanwhile distinctly several other pairs difficult to be observed 

 in twilight ; but, within an hour afterwards, he found it double 

 in all its splendour. One is tempted to think that he must 

 have been previously looking at the wrong star, but he does not 

 seem to have suspected this himself. The Roman astronomers 

 in 1842 described an imaginary comes lying nearly between the 

 two stars ; but this was not their only blunder of the kind. Their 

 telescope — a very fine one, with a 6-i-inch object-glass by 

 Cauchoix, had this imperfection, and they, unfortunately for 

 their reputation, published its defects as discoveries. Sestini, 

 De-Vico's assistant at Eome, gave the colour of the smaller 

 star yellowish with the Cauchoix telescope. Admiral Smyth 

 has republished in his vEdes Hartwellianao, a detailed com- 

 parison of the colours of 109 stars as noted once by Sestini, and 



