OCCULTATION OF SATURN, 1859. 445 



line which extends from the nucleus to a distance considerably 

 above the point where the star crossed. When Arcturus 

 arrived here this dark space was perfect up to the star, but on 

 the other side the white light of the tail appeared to come 

 quite up to the star ; in short, the bright part of the tail was 

 darkened in the vicinity of the star, and the dark part was 

 brightened, at least so much of it as was on the side farthest 

 from the nucleus. 



1 1 saw the notch again on the opposite side previous to 

 emersion, and then lost it by clouds. 



1 The effects I have described are, doubtless, optical, and 

 the notch and areola evidently due to the bright light of this 

 star ; the effect on the dark central part is not so easy to 

 explain/ 



NOTE ON OCCULTATION OF SATURN, 1859. 



Proc. Astronomical Society, May 8, 1859. 



I OBSERVED the occultation of Saturn with a six-foot tele- 

 scope, 4*3 inches aperture, power 165. I imagined that upon 

 the moment of first contact the ring was a little drawn out 

 into a point, succeeded by a knot or apparent excrescence ; 

 but on thinking it over since it has occurred to me that, as I 

 could not see the edge of the moon's dark limb, and had no 

 clock or means to advise me of the moment of impact, the 

 effects I noticed might well have been due to the cutting 

 off, or, as it were, sharpening the point of the ring by the 

 oblique incidence. I mention the apparent effect, however, as 

 if better observers have noticed it there may be something 

 in it as a corroboration. Excepting this, from the impact 

 until the total disappearance, I could not notice the slightest 

 distortion. 



On the emergence the extremely faint light of Saturn, con- 

 trasted with the moon, was very remarkable ; Saturn was a 

 mere ghost of himself, a faint grey-blue shadow. The line of 

 the moon's edge was perfect, and no dark band was percep- 



