12^ Mr.'9iGorr\Obfervatlons 



At Its greated brightnefs 44 =t hours. 



In decreafins: - - 62 dr hours. 



At its leafl brightnefs 30 ± hours. 



In increaiing - - S^ — ^^o^^s. 



All thefe changes, which hitherto feem to be regular and con- 

 flant, are performed in 7 days 4 hours 38 — minutes; this Ifhali 

 il:ile its period, and hereafter will fhew how it is determined 

 with fuch exa6lnefs. 



The ftars to which ^ Antinoi was Compared are in order 

 thus : ^ Aquil^e third magnitude, /3 Aquilas and 5 Serpentis 

 fourth magnitudes, i Antinoi fourth or f fth magnitude, and ^, 

 Aquilas a bright fifth. I find, by feveral years obfervation, 

 that /3 Aqullas retains the fame brightnefs. ; Antinoi, which 

 has been examined with particular attention by Mr. Good- 

 rick e and myfelf, is fufpe(£ted by us both to be fubject to ar 

 fmall variation, but not fufficiently appar^ent, fo as to afted: 

 materially thefe comparilons, and poffibly it may be only the 

 effedt of fome optical iliuiion ; for I have frequently remarked, 

 that both in the twilight and moon- light, or when the air is in 

 the leafl hazy, there is a greater difference between the bright- 

 nefs of many of the ilars, than in a dark night and clear fky. 

 In the following journal of obfervations of 17 Antinoi, the 

 Greek letters /3, ^, jt*, belong to Aquila, and ;, v, to Antinous ; 

 fecondly, the magnitudes marked in column the third are by 

 eflimation, and can be of no further ufe than merely to give, 

 at firft fight, an idea of the ftar's brightnefs ; and laftly, the 

 lines diftinguifhed by inverted commas, are extra«5ts from Mr, 

 Goodricke's journal, whofe friendly afliflance I have often ex* 

 perienced, and was the more welcome on this occafion, becaufe 

 repeated attention and great exadnefs were requifite, 



K Dates. 



