Astronomical Society. 63 



of Saturn and its ring. This appearance was first noticed by M. 

 Schwabe on December 21, 1827, and has since been confirmed by 

 several persons to whom M. Harding had communicated the cir- 

 cumstance. It seems that the space on the eastern side of the planet 

 appears larger than the space on the western side. M. Harding 

 was at first inclined to treat the whple as an optical deception, till 

 the fact was confirmed by others, when he was induced to attempt 

 an explanation of the phenomenon. He endeavoured to account 

 for it by the present position of Saturn ; but the result of his cal- 

 culation proved that that cause would not increase the space (in 

 March) more than Vs-; a quantity probably too small to become 

 perceptible to the eye. He indeed imagined that the appearance 

 might be caused by the shadow of the body, which at present falls 

 much beyond the south-eastern part of the ring, and which might 

 render it impossible to perceive the equality of the two spaces. 

 But this, he says, is disproved by the observation of M. Schwabe^who 

 saw the same phenomenon on the 31st of December, three weeks 

 before the opposition, when the shadow was on the western side, 

 and could be but faintly discerned. M. Harding is unable to ex- 

 plain it as an optical deception, and yet cannot consider it in any 

 other light at present. Actual measurement, he says, can alone 

 decide the question. He has already written to M. Struve to take 

 some measures with his powerful telescope, and he requests that 

 this communication may, with the same view, be forwarded to 

 Messrs. Herschel and South, who have the best means, in this coun- 

 try, of determining this singular phenomenon. 



Mr. South then read a note, which he had annexed to the above 

 communication, stating that in compliance with M. Harding's 

 wishes, Mr. Herschel and himself had directed their attention to 

 Saturn, but that they did not detect any inequality in the two spaces 

 above alluded to, by means of micrometers attached to his 5-feet 

 equatorial. The mean of 35 measures, taken on April 26, April 29, 

 and May 8, gave the preceding (or western) space 3"*532; and the 

 following (or eastern) space 3"*607. At the same time he remarks 

 that the mean of 20 measures taken on April 26 (viz. 10 by 

 Mr. Herschel and 10 by himself) gave the spaces precisely the 

 same ; each being 3"*472. Mr. Herschel's measures gave the pre- 

 ceding (or western) space 3"*612; and the following (or eastern) 

 space 3"*442 ; whilst his own gave the former 3"*331, and the lat- 

 ter 3"-502. Mr. South adds, however, that Mr. Herschel, after a 

 careful examination, thought that, beyond all doubt, the following 

 (or eastern) space appeared the larger: and it is a remarkable 

 fact, that of seven persons who were present in Mr. South's ob- 

 servatory shortly afterwards, and who successively viewed Saturn 

 through his 5-feet equatorial, six of them gave it as their opinion 

 that the apparent right (or eastern) space was the larger : whilst 

 the other observer declared he could not distinguish any difference. 

 The situation, however, of Saturn was so low, as to render most of 

 these observations far from satisfactory. 



M. Harding also alludes in his letter to the reappearance of the 



variable 



