NOTES ON SATURN. • 73 



NOTES ON SATURN. 



By Prof. George Davidson, A. M., Ph. D. 



After midnight of Friday, tbe 13tli 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 ans}>3; 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 ansEe 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 j)lanet 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. Cal. Acad. Sci. H. 5. Issued April 23, 1886. 



