The Planet Saturn. 145 



where it crosses the globe. Various cases of projection and 

 degrees of illumination arise from the changing, and some- 

 times opposite positions of the sun and earth with regard to 

 the ring-plane. When this stands nearly edgeways to both, the 

 ring and its shadow maybe alike invisible (1848, Dawes, Sept. 

 1, 13. Schm : Sept. 6, 14, 17, 18). If the sun and earth are 

 both on the same side, and equally elevated, the ring will hide 

 the shadow, but may be itself perceptible as a grey stripe 

 from the duskiness of C, and the greater part of B, to which 

 possibly the enfeebling of the solar light through the c ' hori- 

 zontal misty air" of its own atmosphere may contribute (see 

 Schwabe's observation infra of the progressively fading ring, 

 1845). If the sun is higher than the earth above the ring- 

 plane, the shadow will be visible beneath it, and A and B will 

 be relieved upon the ball between two unequally dark borders,* 

 C on the one side, and the true shadow on the other — a 

 beautiful sight. If the earth be the higher, the shadow of A 

 and B will be lost sight of behind C, the nearer part of which 

 it ought to render deeper in shade. I do not know that it has 

 been seen to do so ; but in this position Dawes failed to dis- 

 tinguish the shadow of C from C itself across the ball. If the 

 sun and earth are on opposite sides of the plane, and each 

 sufficiently removed from it, the ring and its shadow will come 

 out as two dark lines crossing the ball, with an extremely 

 narrow bright streak, a portion of the ball's surface, between 

 them. This extremely minute object, though repeatedly seen,f 

 has not been always visible when we might have expected it ; 

 the difference might arise from a change in the position of the 

 plane of C (we may here remark, by the way, that if were 

 materially thicker than the other rings, it is scarcely conceiv- 

 able that this streak of light should be ever visible) ; or it 

 might be referred to the presence of an atmosphere ; some 

 possible indications of which we shall now be better able to 

 appreciate. 



During the decrease of the ring in 1845, Schwabe found 

 it gradually diminishing in reflective power, till from being in 

 July always brighter than the ball, it had become equal in 

 September, and by Oct. 11, a trifle fainter, and at the same 

 time more of an orange-grey. This went on increasing, and 

 he could only exceptionally note the colours alike, though the 

 ring was always the fainter. After Nov. 21, it was always 

 much the darker, especially on the W. side. — 1848. June 30, 



* 1851, Oct. 26. Dawes saw both equally black, but in consequence of their 

 falling on very unequally reflective parts of the ball. 



t Intellectual Observer, ix. 381, where it is erroneously stated never to 

 be mentioned by the American observers. See Bond L, 1848, Nov. 22. To the 

 instances of visibility there given, should be added 1861, Dec. 4, Jacob. — 

 1862, May 13, Talmage. 



VOL. X. — NO. II. L 



