X4-(S °N TWO CELESTIAL BODIES. 



Others will foon As I have given a definition which is fufficiently extend ve to 

 be found outj i3 ^ Q in f uture difcoveries, it may be proper to Hate the reafons 

 we have for expecting that additional afteroids may probably 

 be foon found out. From the appearance of Ceres and Pallas 

 it is evident, that the difcovery of afteroids requires a particular 

 method of examining the heavens, which hitherto aftronomcrs 

 have not been in the habit or* ufing. I have already made five 

 reviews of the zodiac, without detecting any of thefe concealed 

 objects. Had they been lefs refembling the fmall ftars of the 

 by obferving the heavens, I muft have difcovered them. But the method which 

 « weluTthe" w '^ n0w ^ e P ut m practice, will completely obviate all difti- 

 appearanceof culty arifing from the afteroidical appearance of thefe objects ; 

 as their motion, and not their appearance, will in future be the 

 mark to which the attention of obfervers will be directed. 

 Society for that A laudable zeal has induced a fet of gentlemen on the 

 Continent, to form an aflbciation for the examination of the 

 zodiac. I hope they will extend their attention, by degrees, to 

 every part of the heavens; and that the honourable diftin&ion 

 which is juftly due to the fuccefsful inveftigators of nature,, 

 will induce many to join in the meritorious purfuit. As the 

 new method of obferving the zodiac has already produced fuch 

 interefting difcoveries, we have reafon to believe that a number 

 of afteroids may remain concealed; for, how improbable it 

 would be, that if there were but two, they fliould have been 

 fo near together as almoft to force themfelves to our notice. 

 But a more extended confideration adds to the probability that 

 many of them may foon be difcovered. It is well known that 

 the comas and tails of comets gradually increafe in their ap- 

 proach to the fun, and contract again when they retire into the 

 Comets may be- diftant regions of fpace. Hence we have reafon to expect, 

 ' that when comets have been a confiderabletime in retirement, 

 their comas may fubfide, if not intirely, at leaft fufficiently to 

 make them aflume the refemblance of ftars ; that is, to become 

 afteroids, in which ftate we have a good chance to detect, them. 

 It is true that comets foon grow fo faint, in retiring from their 

 perihelia, that we Iofe fight of them; but, if their comas, 

 which are generally of great extent, (hould be comprefled 

 into a fpace fo fmall as the diameters of our two afteroiefs, we 

 can hardly entertain a doubt but that they would again become 

 and beobferved vifible with good telefcopes. Now, fliould we fee a comet 

 mj eir ap e- > m ^ a p ne |j on ^ un der the conditions here pointed out, and that 

 there are many which may be in fuch fituations, we have the 



great eft 



