562 BIBLIOGRAPHY OF HERSCHEL's WRITINGS. 



Herschel, W.: Synopsis of the Writings of— Continued. 



A. D. Tol. P. 



IV is dusky, dingy, inclining to orange, reddish, and ruddy at differ- 

 ent times ; and these tints may induce us to surmise that this satel- 

 lite has a considerable atmosphere. 



1797 87 350 The diameter of the second satellite is 0".87 hy 1 ohs. 



351 III is considerably larger than any of the rest ; I is a little larger than 

 II, and nearly of the size of IV ; II is a little smaller than I and IV, 

 or the smallest of all. 



Wm. Herschel. 

 [Dated] Slough, near Windsor, April 30, 1797. 



1798 83 47 On the discovery of four additional satellites of the Georgium Sidus, The 



retrograde motion of its old Satellites announced, and the cause of their 

 Disappearance at certain distances from the Planet explained. By Wil- 

 liam Herschel, LL. D., F. R. S. Read December 14, 1797. 



47 I have lately recomiiuted ray observations of the satellites of [ Uranus'] 



with improved tables from 1787 to now. I laid down a set of the- 

 orems relating to the motions of these satellites ; I calculated tables 

 and devised means for checking the computations. 



48 I here announce that the motion of the Georgian satellites is retro- 



grade. 

 48 From my miscellaneous observations, the existence of four additional 

 satellites will be proved ; the observations which tend to ascertain 

 the existence of rings to the planet not being satisfactorily sup- 

 ported, this surmise will be given up, or left till sui^erior instruments 

 are provided. 



48 Observations of stars near the planet are given under the head Be- 



ports, and of the new satellites under the head Observations. 



49 Investigation of additional satellites. « 



58 Arguments upon the Eeports and Observations. 



An interior satellite. [The observations described.] 



62 An intermediate satellite. [The observations described.] 



63 An exterior satellite. [The observations described.] 



64 The most distant satellite. [The observations described.] 



66 The arrangement of the satellites together will be thus : 

 First satellite, the interior one of Jan. 18, 1790. 

 Second satellite, the nearest old one of Jan. 11, 1787. 

 Third satellite, the intermediate one of ilar. 26, 1794. 

 Fourth satellite, the farthest old one of Jan. 11, 1787. 

 Fifth satellite, the exterior one of Feb. 9, 1790. 



Sixth satellite, the most distant one of Feb. 28, 1794. 



67 Observations and reports tending to the discovery of one or more rings of 



tlie Georgian Planet and the flattening of its Polar Eegions. 



69 Bemarlcs iipon the foregoing observations. 



70 The observation of the 26th Feb., 1792, seems to be very decisive 



against the existence of a ring, etc., and I venture to affirm that 

 the planet has no ring in the least resembling those of Saturn. 



70 The flattening of the poles of the planet seems to be sufficiently as- 



certained. 



71 This being admitted, we may conclude that the Georgian Planet also 



has a rotation on its axis of a considerable degree of velocity. 



71 Eeports and observations relating to the light and size of the Georgian satel- 

 lites, and to their vanishing at certain distances from the Planet. 



73 Reinarks on the foregoing observations. 



73 Small srars near the iilanet lose much of their lustre. 



