21Q ttAUSE or THE CHANGES Of RELATIVE 



XI. 



Account of the Changes that have happened, during the laft Tvcenty- 

 Jive Years, in the relative Situation of Douhle-Jiars ; with an 

 Invejligation of the Caufe to which they are owing. By Wil- 

 liam Herschel, LL. D. F.RS. from the Philofophical 

 Tranfaaions for IS03 . 



Read June 9, 1803. . 



General ob'er- 1n the Remarks on the Con(lrii6lion of the Heavens, con- 

 Ihfo^ry'oTthe* t^^n^^ >" "^X ^^^ ^^P^^ ^n this fubjeft,* I have divided the va- 

 heavenly bodies, rious objeds whicli aftronomy has hitherto brought to our view. 

 Into twelve clalFes. The firft comprehends infulated ftars. 



As the folar fyftem prefents us with all the particulars that 

 piay be known, refpe6ting the arrangement of the various fu- 

 bordinate celeftial bodies that are under the influence of ftars 

 which I have called infulated, fuch as planets and fatellites, 

 • afteroids and comets, I fliall here fay but little on that fubjed. 

 It will, however, not be amifs to remark, that the late addition 

 of two new celeftial bodies, has undoubtedly enlarged our know- 

 ledge of the conftruftion of the fyftem of infulated ftars. 

 Whatever may be the nature of thefe two new bodies, we know 

 that they move in regular elliptical orbits round the fun. It is 

 not in the leaft material whether we call them afteroids, as I 

 have propofed ; or planetoids, as an eminent aftronomer, in a 

 letter to me, fuggefted ; or whether we admit them at once into 

 , the clafs of our old feven large planets. In the latter cafe, how- 

 ever, we muft recoiled, that if we would fpeak with precilion, 

 they (hould be called very fmall, and exzodical ; for, the great 

 inclination of the orbit of one of them to the ecliptic, amounting 

 to 35 degrees, is Certainly remarkable. That of the other is alfo 

 confiderable ; its latitude, the laft time I faw it, being more 

 , than 15 degrees north. Thefe circumftances, added to their 

 fmallnefs, fliow that there exifts a greater variety of arrange- 

 ment and fize among the bodies which our fun holds in fubor-» 

 dination, than we had formerly been acquainted with, and ex- 

 tend our knowledge of the conftrudion of the folar, or infulated 

 fidereal fyftem. It will not be required that I fliould add any 



* See Phil. Tranf. for 1802, p. 477, and oar Journal, V. 72, 



thing 



