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Observations and Remarks on the Figure, the Climate, and the Atmo- 

 sphere of Saturn, and its Ring. By William Herschel, LL.D. F.R.S. 

 Read June 26, 1806. [Phil. Trans. 1806, p. 455.] 



The observations made by Dr. Herschel last year, on the figure of 

 Saturn, having drawn the attention of astronomers to the subject, a 

 further investigation of it appeared to him to be necessary. Those, 

 he says, who compare his former figures of the planet (in which the 

 particular shape of the body was not meant to be represented,) with 

 that annexed to his last paper, and wonder at the difference between 

 them, have not attended to the measures he had given of the equa- 

 torial and polar diameters of it; these, as established in 1789, are 

 the same as in his last figure, which differs only in having the flat- 

 tening at the pole a little more extended on both sides ; and as his 

 attention, in 1789, was entirely taken up with an examination of the 

 two principal diameters of the planet, it is not, he thinks, extraordi- 

 nary that the singularity of its shape should then have been over- 

 looked by him. 



After some observations on the magnifying powers necessary to 

 be used in observing the figure of Saturn, Dr. Herschel proceeds to 

 relate the observations made by him, for that purpose, in the months 

 of April, May, and the beginning of June, of the present year. He 

 first, however, gives an observation made in the year 1788, from 

 which it appears, that he had then observed the shape of Saturn not 

 to be spheroidical (like that of Mars or Jupiter), but much flattened 

 at the poles, and a little flattened at the equator. 



The observations made this year by our author, agree with those 

 made last year, in establishing, that the flattening at the poles of 

 Saturn is more extensive than it is in Jupiter : also that the curva- 

 ture hi high latitudes is greater than in the last-mentioned planet ; 

 but, on the contrary, the curvature at the equator is rather less in 

 Saturn than it is in Jupiter. 



In the observation of May 16, of the present year, the greatest 

 curvature in the disc of Saturn appeared to be at the latitude of 

 about 40. 



Upon the whole, the figure of Saturn may, Dr. Herschel says, be 

 called a spheroid, while that of Jupiter may be called an ellipsoid. 



Our author now proceeds to notice some observations he has made 

 on the periodical changes in the colour of the polar regions of Saturn. 

 From those made in the years 1793, 1794, and 1796, when the south 

 pole of the planet had been long exposed to the influence of the sun, 

 it appeared that the regions about that pole had lost their former 

 whiteness ; and that the whiteness of the northern hemisphere was 

 increased. Those made in the present year, when the north pole of 

 Saturn is exposed to the sun, show that its regions have lost much 

 of their brightness ; while those about the south pole have regained 

 their former colour, and are brighter, and whiter, than the equatorial 

 parts. 



Respecting the atmosphere of Saturn, Dr. Herschel observes, that 



