NOTES. CXXXVU 



( 618 ) p. 379. Kosmos, Bd. ii. S. 357359 and 509, Antn. 44; Engl. ed. 

 p. 316318, and cziv. Note 484. 



( 619 ) p. 380. Sir John Herschel, Outlines, 540. 



( 62 ) p. 381. The earliest careful observations of William Herschel, in 

 Nov. 1793, gave for the rotation of Saturn 10 hours, 16 minutes, 44 seconds. 

 It has been erroneously stated, that, forty years before William Herschel, the 

 great philosopher Kant, in his ingenious Allgemeine Naturgeschichte des 

 Himmels, inferred truly the time of rotation of Saturn from theoretical con- 

 siderations. The number which he assigned was 6 hours, 23 minutes, 53 

 seconds. He called his determination the " mathematical computation of an 

 unknown movement of a heavenly body, which is perhaps the only prediction 

 of its kind in natural science, and must await its confirmation from future 

 observations." The hoped-for confirmation did not arrive ; on the contrary, 

 observation has shewn that the anticipation was in error 4 hours, or three- 

 fifths of its amount. In the same work he says of Saturn's ring, that of the 

 accumulated particles of which it consists, those of the interior margin per- 

 form their course in 10 hoars, and those of the exterior margin in 15 hours. 

 The first of these two numbers, applied to the ring, is the only one which is, 

 accidentally, near to the observed time of rotation of the planet. Compare 

 Kant, Sammtliche Werke, Th. vi. 1839, S. 135 and 140. 



( 621 ) p. 381. Laplace (Expos, du Syst. du Monde, p. 43) estimates the 

 compression at the poles at %. The singular supposed deviation of Saturn 

 from a spheroidal figure, in conformity with which William Herschel, by a 

 series of elaborate observations, made, moreover, with very different telescopes, 

 found the major axis of the planet, not in the equator itself, but in a diameter 

 crossing the equatorial diameter at an angle of about 45, has not been con- 

 firmed by Bessel, but, on the contrary, was believed by him to have been 

 erroneous. 



( 622 ) p. 382. Arago, Annuaire pour 1842, p. 555. 



( 623 ) p. 382. This difference of the intensity of light of the inner and the 

 outer ring was already noticed by Dominique Cassini (Mem de 1' Academic 

 des Sciences, Annee 1715, p. 13). 



( 624 ) p. 382. Kosmos, Bd. ii. S. 359 ; Engl. ed. p. 318319. The^-' 

 lication of the discovery, or rather of the complete explanation of all the 

 phsenomena presented by Saturn and his ring, was not made until four years 

 later, in 1659, in the Systema Saturnium. 



( b " 25 ) p. 384. Such mountain-like inequalities have recently been noticed by 



