444 EXPERIMENTAL INVESTIGATIONS. 



inverting eye-glasses are used, is in many instances pseudo- 

 scopic, the more distant objects appearing nearer than the 

 more proximate, which is the effect that theory would 

 indicate. 



The satellite, last in order on emersion, seemed to cling 

 for a second or so to the moon's edge, probably an effect due 

 to irradiation. I did not observe this with the three others, 

 but I did not catch the moments of emersion so well with 

 them. I was greatly struck by the beautiful impression con- 

 veyed to the mind by the binocular telescope ; and judging 

 from what I had seen with a monocular telescope of my own, 

 of 4*3 inches aperture, and therefore not far differing in area 

 from the compound area of the two object-glasses in the 

 binocular, the latter was decidedly superior, and the ease and, 

 if I may be allowed the expression, the naturalness of the 

 vision, was very remarkable. 



NOTE ON COMET V. 1858. 

 Proc. Astronomical Society ', Nov. 12, 1858. 



THE following extract from a letter adressed by Mr. Grove to 

 Mr. De La Rue refers to the phenomena observed during the 

 transit of the tail of the comet over Arcturus on the evening 

 of October 5. The telescope employed by Mr. Grove was 

 a small instrument, of only two inches aperture, and his re- 

 marks are offered under an impression that the weather else- 

 where was not generally favourable for observing the comet on 

 the interesting occasion to which they refer : 



' When the comet had entered well within the margin of 

 the tail a dark notch was formed, cutting out a portion of the 

 tail round the star ; and as the star got farther in, this became 

 a dark areola surrounding the star, and in diameter equal to 

 about one-tenth of the line of transit. This continued until 

 the star reached the middle ; at this part there is a broad dark 



