5l7$ VARIABLE. STAR*. 



3 J View, . 

 Another caufing F|g, 5, We will now apply a cafe of an interval of loo great 

 rcntly lone. ' length, that of 72 days: the fpot m alone having fliewn us 

 the flar in:it« M luftre, its Hgfet difappears during tlie revo- 

 lution, and another brightens forth ten days (or 5S decrees) 

 following it at H ; when 7/1 returns to face us again in 62 days 

 it being obliterated, the ftar will appear obfcured, and not 

 recover its f^;)len(iour until the new brightened part H becomes 

 central, whidi being ten days later than the petition in which 

 m was feen, makes the revolution 72 days inftead of 62, as 

 was obferved between July 14 and September 24, 18G1. (See 

 Table IX.j In the above cafe the alterations took place while 

 behind the flar, olherwife fome irregularities would have been 

 perceived, as will later be noticed. The fame reafoning with 

 proper alterations will, I apprehend, account for th<e other re- 

 volutions, yet I flifill fpon again refume th^ fubjedl with re- 

 gard to 3L /tries of the greateft irregularities ; at prefent let us 

 proceed to take a few views of the intervals of Its leajl bright" 

 ncfst which^ contrary to mj ,expe£"t,alio,n, J find much a?ore 

 diflicult to ji^xp^^t) than thqfe of the full, ^jthqugh Ih^ refults 

 difagree.lels among them.felves. , .Tbe fiarkened face of the 

 flar is here r*Qprefen(ed vyiUi a few fmall changeable bright 

 fpots, pjaced in general ^t a proper diftance, fo as to keep up 

 ^n uninterrupted increafe and decreafe of light with regard 

 to us, ^nd are alfo made to correfpond with feveral other 

 obfervations, 



4siJt f'iezs, 



Grcatftft period Fig 4 is to explain the greateft interval of 74 days, 



explained; be- between July 4th,' and September J frth 1799. (See Table X») 

 tween intervals , '^ ,.,.,.. . . , , 



of leaft bright- -i '^® darkened nemnpnere here exhibited in its mmwium July 



ncfs* 4th, with the following fpots, w nearly gone off", next a fmall 



one /, then aiKJther P of a fimilar fize, preceding the centre a 



day or two, (or a few degrees, (and lafily a bright one at D, 



juft appearing. During the rotation, D loiing its light and the 



P becoming much brighter, the ftar at its next return in 62 days, 



when at its firfl pofition, muft of courfe appear much brighter, 



(See fig. 5) but by the retiring of / and P continues to dimi- 



nifh in luffre till the appearance of fome large fpot from the 



other he mifphere; which taking place 1 2 days afterwards, will, 



(when this time is added to the 62 already revolved] make the 



rovolu^n 



