OF ARTS AND SCIENCES. 259 



" On the 16th uhimo, I was prepared with a five-foot equatorial in- 

 strument of. four-inch aperture, and an excellent chronometer by Par- 

 kinson and Frodsham. My assistant was furnished with a forty-two- 

 inch Dolland, of three-inch object-glass, and a chronometer by Robert 

 Roskell. The error and rate of my chronometer were obtained by 

 the sun's meridian passage at the previous and the succeeding noon, 

 and confirmed by the meridian passage of Antares on the following 

 evening. With this chronometer that used by my assistant was com- 

 pared before ar!d after the occultation, and no change detected. The 

 immersion, as observed by myself, occurred at 9'' 30""- 49' . The 

 time noted by my assistant was 9*"' SO™' 50'-, and the mean of these 

 results, namely, 9''" 30™' 49'. 5 may be deemed the true mean time at 

 the meridian of my observatory. 



" At this immersion of Aldebaran, I witnessed for the third time the 

 singular phenomenon of the projection of the star on the bright limb 

 of the moon. The other instances occurred, first on the 16th of July, 

 1830, and again on the 30th of August, 1831. In the present case the 

 appearance of the star between my eye and the moon was so decided, 

 that a thread of the moon's disc was manifest east of the star, and the 

 star seemed to plunge into the surface of the moon. But this position 

 was assumed by the star instantaneously, and not progressively, as 

 sometimes supposed. The star occupied this position nearly t\\o sec- 

 onds, strictly one second and seven tenths. 



" This illusion, for such it must be called for the want of a better 

 explanation, is well worthy of the consideration of astronomers. In 

 the immersion of other stars of the first magnitude, I have not witnessed 

 it, nor have I met with it in the observations of others. 



"Is this unaccountable appearance peculiar to this star. ^ Whether 

 it be so or otherwise, no inquiry can interest astronomers more than 

 the solution of this mystery." 



Mr. W. C. Bond also communicated a letter from Colonel 

 J. D, Graham, giving an account of the transit of Mercury 

 on the 8th of May, 1845, at Castle William, on Governor's 

 Island, in New York harbor. 



" The observations of Major Graham, in which he was assisted by 

 Lieutenant Thorn, were made with a forty-six-inch achromatic tele- 

 scope constructed by Simms, having an aperture of two inches and 

 three fourths, with a power of sixty, shaded by an orange glass. This 



