Conflrii^llon of the Ihavehs, i^p' 



of Sirius. And, perhaps, in putting it, by the apparent iize 

 of the flars, at 600 only, I may have conliderably under-rated 

 it ; but my argument, if that ihould be the cafe, will be fo 

 much the ftronger. Now to proceed, 



Some of thefe round nebulae have others near them, perfeiflly 

 fuiiilar in form, colour, and the diftribut'ioii of flars, but of only 

 half the diameter: andthe flars in them fecm to be doubly crowded, 

 and only at about half the diilance from each other : they arc 

 indeed lb fmall as not to be vifible without the utmoft attention, 

 I fuppofe thefe miniature nebulae to be at double the diftance of 

 the tirft. An inifance, equally remarkable and inflruclive, is 

 a cafe where, in the neighbourhood of two fuch nebulas as 

 have been mentioned, I met with a third, fimllar, refolvable, 

 but much fmaller and feiinter nebula. The flars of it are no 

 longer to be perceived ; but a refemblance of colour with the 

 former two, and its diminished fize and light, may well per- 

 mit us to place it at full twice the diiliance of the fecond, or 

 about four or five times that of the lirfl:. And yet the nebil- 

 lofity is not of the milky kind ; nor is it {o much as difficultly 

 refolvable, or colourlefs. Now, in a few of the extended ne- 

 bulae, the light changes gradually fo as from the refolvable to 

 approach to the milky kind ; which appears to me an indica- 

 tion that the milky light of nebulae is owing to their much 

 greater diflance. A nebula, therefore, whofe light Is perfedlly 

 milky, cannot well be fuppofed to be at lefs than fix or eight 

 thoufand times the diflanCe of Sirius ; and though the numbers 

 here afiumed are not to be taken otherwife than as very coarfe 

 eftimates, yet an extended nebula, which in an oblique fitua- 

 tiofl, where it is poffibly fore-fhortened by one-half, two-thirds, 

 or Hiree- fourths of its length, fubtends a degree or more in 

 ♦ L 1 i; diameter, 



