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Uniycrsity of California • Berkeley 
 
-/■ 
 
 ASTRONOMICAL NOTES 
 
 From Bulletin No. 5 
 
 OF THE 
 
 California Academy of Sciences. 
 
 BY 
 
 GEORGE DAVIDSON. 
 
 1886. 
 
NOTES ON SATURN. 73 
 
 NOTES ON SATURN. 
 
 By Prof. George Davidson, A. M., Ph. D. 
 
 After midnight of Friday, the 13th November, 1885, the 
 atmosphere was unusually steady; sky clear; no wind; at- 
 mosphere saturated with aqueous vapor; heavy dew falling. 
 The satellites of Saturn were plainly visible with a moder- 
 ate power to the equatorial of 6.4 inches objective. The 
 planet was examined for nearly two hours with different 
 powers, the best effects being obtained with powers of 300 
 to 350 diameters; and the summary of the matters of inter- 
 est is as follows : 
 
 The Encke division was traced for 120^ about each end 
 of the major axis, leaving only 120° not seen. The division 
 was faint but it was there, a little outside the middle of the 
 ring A. 
 
 In the ring B the inner part presented such an appear- 
 ance in its delicate shading as would arise from a rapid hor- 
 izontal rotary motion being given to a disc of irregularly 
 distributed and yielding matter. I could detect no atmos- 
 pheric unsteadiness that would give rise to this phenomenon. 
 
 The dusky ring presented equally distinct ansce; on for- 
 mer occasions I had been satisfied that they were sometimes 
 of different brightness, and had endeavored to find some 
 law for this variation. The dusky ring was well defined at 
 the ansie and across the body of the planet, but I was con- 
 vinced that the limb of the planet was visible through the 
 dusky ring, very nearly, if not quite up to the inner edge of 
 ring B. 
 
 The shadow of the planet was cast upon the preceding 
 side, and where it reached the outer edge of the ring B, it 
 was recurved farther from the planet as if the outer edge of 
 B had a round moulding above the general level of the 
 plane. 
 
 6— Bull. Gal. Acad. Sci. U. 5, Issued April 23, 1886. 
 
74 CALIFORNIA ACADEMY OF SCIENCES. 
 
 The markings of tlie planet were quite distinct. The 
 darker color of the pole was gradually toned down until it 
 met the second moderately faint belt south of the equator. 
 The second belt was quite dark but appeared to have a more 
 marked darkness on the following side of the central line, 
 where it should have been brighter on account of the sun- 
 light. Then came the bright equatorial belt without mark- 
 ings and north of it a narrow dark band about half as broad 
 as the trace of the dusky ring across the planet, with a nar- 
 row dark band about half as broad as the trace of the dusky 
 ring across the planet, with a narrow lighter space between 
 it and the edge of the dusky ring. 
 
 January 8, 1886. The atmosphere was unsteady, but at 
 quiet moments I saw the Encke division by using a power 
 of 250 diameters. Observations made with the Clark Equa- 
 torial of G.4 inches. 
 
 January 25, 1886. The atmosphere was wonderfully 
 steady. I saw the dusky ring of Saturn with powers as low 
 a,s 150 diameters, and the equatorial beltings were beauti- 
 fully sharp. The shape of the shadow on the outer part of 
 the B ring was apparently not so recurved as heretofore. I 
 saw the limbs of the planet through the dusky ring to the 
 inner edge of ring B. I was able to follow the grayish in- 
 ner edge of the B ring across the body of the planet and in 
 contrast with the dusky ring below it. The Encke division 
 at the preceding part of the ellipse was clearly outside the 
 middle of A ; at the following part it was barely outside the 
 middle of A; no difference of breadth of the Cassini divis- 
 ion could be distinguislied at either extreme. 
 
 February 14, 1886. Atmosphere steady. Carried powers 
 to 450 diameters. The Encke division clearly exhibited; 
 on the preceding side it is outside the middle of A, on the 
 following side it is barely inside the middle oi A ; I carry 
 it well down to the narrow part of the ellipse. The dusky 
 -ring is well seen and it seems that the inner edge extends 
 more than half way from B to the planet. The limbs of the 
 
NOTES ON SATURN. 75 
 
 planet are seen through the dusky ring and the inner edge 
 of B, I cannot determine any difference of brightness be- 
 tween the preceding and following parts of the dusky ring. 
 
 I have watched carefully and repeatedly a minute — ex- 
 cessively minute — and white protuberance on each side of 
 the planet apparently off the broad bright equatorial belt, 
 but really at the points where the faintly dark belt nearest 
 the dusky ring disappears at either limb. This would seem 
 to indicate that this faint dark belt is raised above the gen- 
 eral surface of the splieroid. 
 
 March 31, 1886. To this date I have not been able, on 
 account of atmospheric conditions, to test the last observa- 
 tions of February 14. 
 
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