176 COSMOS. 



again to its rainimnm daring eight hours of the latter period, hov^ eve? 

 it scarcely changes at all, and very inconsiderably for a whole day. 



(9) a Herculis, E. A. 256^ 57', Decl. +14° 34'; an extremely red 

 double star, the variation of whose light is in every respect very in-eg* 

 ulai-. Frequently, its light scarcely changes for months together; al 

 (jther times, in the maximum, it is nearly five gradations brighter tha« 

 in the minimum; consequently, the period also is still veiy uncertain. 

 The discoverer of tlie star's variation had assumed it to be sixty -three 

 days, I at first set it down at ninety-five, until a careful reduction of all 

 uiy observations, made during seven years, at length gave me the peri- 

 cxl assigned in the text. Heis believes that he can represent all the ob- 

 servations by assuming a period of 184*9 days, with two maxima and 

 two minima. 



(10) Coronas R., R. A. 2350 36', Decl. -f28^ 37'. This star is varia- 

 ble only at times* the period set down has been calculated by Koch 

 from his own observations, which unfortunately have been lost. 



(11) ScutiR.,R.A. 279^52',Decl.— 5051'. The variations of bright- 

 ness of this star are at times confined within a very few gradations, 

 whereas at others it diminishes from the fifth to the ninth masrnitude. It 

 has been too little observed to determine when any fixed rule prevails 

 in these deviations. The duration of the period is also subject to con- 

 siderable fluctuations. 



(12) Virginis R., R. A. 187° 43', Decl. -{-7° 49'. It maintains its pe- 

 riod and its maximum brightness with tolerable regularity; some devi- 

 ations, however, do occur, which appear to me too considerable to be 

 ascribed merely to errors of observation. 



(13) Aquarii R., R. A. 354° 11', Decl. —16° 6'. 



(14) Serpentis R., R. A. 23.5° 57', Decl. -f 15° 36'. 



(15) SeqDentis S., R. A. 228° 40', Decl. -fH^ 52'. 



(16) Cancri R., R. A. 122^ G', Decl. -f 12^ 9'. 



Of these four stars, which have been but very slightly observed, littis* 

 more can be said than what is given in the table. 



(17) a Cassiopei;e, R. A. 8° 0', Decl. -f-55° 43'. This star is very diffi- 

 cult to obsen'e. The diflerence between its maximum and minimum 

 only amounts to a few gi'adations, and is, moreover, as variable as the 

 duration of the period. This circumstance explains the varying state 

 ments on this head. That which I have given, which satisfactorily rep 

 resents the observations from 1782 to 1849, appears to me the mostprob 

 able one. 



(18) a Orionis, R. A. 86° 4G', Decl. 4-7° 22'. The variation in the 

 light of this star likewise amounts to only four gradations from the min- 

 imum to the maximum. For Ql\ days it increases in brightness, while 

 its diminution extends over 104^, and is imperceptible from the twen- 

 tieth to the seventieth day after the maximum. Occasionally its varia 

 bility is scarcely noticeable. It is a xerv red star. 



(19) a Hydrfe, R. A. 140° 3', Decl. —8^ 1'. Of all the variable stars, 

 this is the most difficult to observe, and its peiiod is still altogether un-« 

 certain. Sir John Herschel sets it down at f om twenty-nine to thirty 

 days. 



(20) e Aurigfc, R. A. 72^ 48', Decl. 4-43'^ 3G'. The alteraation of 

 light m this star is either extremely irregular, or else, in a period of sev- 

 eral years, there are several maxima and minima — a question which can 

 not be decided for many years. 



(21) C Geminorum, R. A. 103^ 48', Decl. +20^ A7'. This star has 

 hitherto exhibited a perfectly regular course in the Variations of its lig'^t 



