PLEASURES OF THE TELESCOPE. 517 



75. 2 2744 consists of two stars, magnitudes six and seven, dis- 

 tance 1'6", p. 171. It is probably a binary. 2 2742 is a wider 

 double, magnitudes both six, distance 2*6", p. 225. Another 

 triple, one of whose components is beyond our reach, is y. Here 

 the magnitudes are fifth, twelfth, and sixth, distances 2", p. 274, 

 and 366". It would also be useless for us to try to separate S, but 

 it is interesting to remember that this is one of the closest of 

 known double stars, the magnitudes being fourth and fifth, dis- 

 tance 0'4", p. 198. These data are from Hall's measurements in 

 1887. The star is, no doubt, a binary. With the five-inch we 

 may detect one and perhaps two of the companion stars in the 

 quadruple (3. The magnitudes are fifth, tenth, and two eleventh, 

 distances 67", p. 309 ; 86", p. 276 ; and 6-5", p. 15. The close pair 

 is comprised in the tenth-magnitude star. 



Map No. 19 introduces us to the constellation Pegasus, which 

 is comparatively barren to the naked eye, and by no means rich 

 in telescopic phenomena. The star e, of magnitude two and a half, 

 has a blue companion of the eighth magnitude, distance 138", p. 

 324 ; colors yellow and violet. A curious experiment that may 

 be tried with this star is described by Webb, who ascribes the 

 discovery of the phenomenon to Sir John Herschel. When near 

 the meridian the small star in e appears, in the telescope, under- 

 neath the large one. If now the tube of the telescope be slightly 

 swung from side to side the small star will appear to describe a 

 pendulumlike movement with respect to the large one. The ex- 

 planation suggested is that the comparative faintness of the small 

 star causes its light to affect the retina of the eye less quickly 

 than does that of its brighter companion, and, in consequence, 

 the reversal of its apparent motion with the swinging of the tele- 

 scope is not perceived so soon. 



The third-magnitude star 17 has a companion of magnitude ten 

 and a half, distance 90", p. 340. The star (3, of the second magni- 

 tude, and reddish, is variable to the extent of half a magnitude in 

 an irregular period, and y, of magnitude two and a half, has an 

 eleventh-magnitude companion, distant 162", p. 285. 



Our interest is revived on turning, with the guidance of map 

 No. 20, from the comparatiye poverty of Pegasus to the spacious 

 constellation Cetus. The first double star that we meet in this 

 constellation is 26, whose components are of magnitudes six and 

 nine, distance 16*4", p. 252 ; colors, topaz and lilac. Not far away 

 is the closer double 42, composed of a sixth and a seventh magni- 

 tude star, distance 1*25", p. 350. The four-inch is capable of 

 splitting this star, but we shall do better to use the five-inch. In 

 passing we may glance at the tenth-magnitude companion to rj, 

 distant 225", p. 304. Another wide pair is found in , magnitudes 

 third and ninth, distance 185", p. 40. 



