102 IRREGULARITY OF THE PLANET SATURN, 



me know whether he could perceive any difference in the ap- 

 pearance of their curvature; in answer to which I received, 

 the 23d of June, a letter enclosing a drawing, in which also 

 the southern regions were marked as more protuberant, with 

 a greater falling off close to the irregularity. My friend, 

 with his usual precaution, calle&ithis an illusion; and it will 

 be seen by and by, that we shall have no occasion to ascribe 

 this irregularity to a real want of due proportion, or settled 

 figure of the polar regions of Saturn. 



June 22, 9n 24'. I see the same curved appearance at 

 the south pole of Saturn, which was observed the l6th. 



June 24. The air is very clear, and all the most critical 



phenomena are very distinctly to be seen ; the shadow of 



the ring towards the south upon the planet; the shadow of 



the body towards the north-following side upon the ring; 



the belts upon the body ; the division of the two rings; and 



with the same distinctness, I also see the protuberance of 



the south pole. 



Not a distortion My seeing this appearance, at present, is a proof, that it 



° f f " 1 ! r^" * s not a phy s » ca l irregularity or distortion of only some par- 



the polar re- ticular spot on the polar regions; for, in that case, it could 



? l0n ' not have been seen this evening, as from the rotation of the 



planet on its axis, which is lOh l6', the space of the polar 



circle which is now exposed to our view must have been 



very different from what I saw the l6th and 22d. 



Many observations were made afterward, which all confirm 

 the reality of this appearance. 

 It is probably It is so natural for us to reflect upon the cause of a new 

 an illusion, phenomenon, that I cannot forbear giving an opinion on this 

 subject. To suppose a real change in the whole zone of the 

 planet, cannot be probable ; it seems therefore, that this ap- 

 pearance must be, as my friend calls it, an illusion. But 

 since the reality of this illusion, if I may use the expression, 

 has been ascertained by observation, it is certain, that there 

 irrust be some extrinsic cause for its appearance; and also 

 that the same cause must not act upon the northern hemis- 

 phere. Now the only difference in the circumstances under 

 which the two polar regions of Saturn were seen in the fore- 

 going 





