i'62 Mr. GooDRicKE*s Obfervat'ions 



becaufe in that point the flar has been obferved of about the 



fourth magnitude at intervals much fhorter than in the third 



point, fo that, if it had continued to diminifli, its diminution 



would have proceeded at a more rapid rate, which ftill fhews 



that there is at leaft a difference between thefe two points. 



With regard to the period of the variation, it is evident 



from a collation of the preceding obfervations in a coarfe way, 



that it is nearly twelve days and three quarters. To determine it 



with greater accuracy is a fubje6t of confiderable difficulty, in 



the prefent cafe ; for unlefs we can obtain very exa6l points of 



comparifon, the period would come out erroneous, efpecially 



if deduced from intervals confifting. of only a very few periods, 



as is the cafe here. However, as I have been able to obtain a 



few obfervations of the middle of its obfcuration in the third 



point accurate enough for our purpofe, I have formed the fol« 



lowing calculation. 



Times of the middle of its obfcuration 

 in the third point. 



1784, oa. 6 

 — 18 

 oa. 18 



— 3^ 



oa. 6 



- 31 



Hence the period on a mean is 1 2 1 9 :±: 

 In afcertaining the above times, I attended particularly to 

 the neareft obfervations both preceding and following. In the 

 manner above ftated the period may alfo be deduced from the 

 middle of its obfcuration in the feventh point ; but as thefe 

 obfervations are not fo exaa as the above, I Ihall only, as a 



further 



