Astronomical Society. 229 



star A, and nearer to C than to A. It is therefore, beyond all doubt, 

 a comet ; and as its place coincides so exactly with the calculated 

 place of Encke's coiiiet, it can be no other than it. 



" Wednesday. November 5th. — This evening, at Slough, the comet 

 was seen in the 7-feet, the 10-feet, and 20-feet reflectors, by Mr. 

 Herschel, Lord Ashley, Dr.Wallich, and myself; since which time 

 1 have frequently seen it with the 5-feet equatorial ; and on Wed- 

 nesday night last, the moon being seven days old, and but a few 

 degrees distant, it was still vi&ible, and was seen by two of my vi- 

 sitors and myself." 



Dec. 12. — The first paper read this evening was the following: 

 Occultations of Aldebaran by the Moon, in the year 1829, com- 

 puted for ten different observatories in Europe, at the request of 

 the Council of this Society, by Thomas Henderson, Esq. of Edin- 

 burgh, and Thomas Maclear, Esq. of Biggleswade, in Bedfordshire. 



The object of the Council, in procuring these computations, lias 

 been to induce astronomers to look out for the occultations, with a 

 view principally to determine whether Aldebaran will appear pro- 

 jected on the face of the moon, as has frequently been observed in 

 former occultations of this star. 



The next paper was " On the determination of the Constant of 

 Aberration of Light, from 4119 observations made at the Iloyal 

 Observatory at Greenwich, during the years 1825, 1826, 1827, and 

 1828, with the two mural circles of Troughton and Jones, by Mr. 

 William Richardson." The author remarks, that, after the great 

 labour bestowed on the subject of aberration by those eminent astro- 

 nomers, Bradley, Delambre, Bessel, Lindenau,Brinkley,and Struve, 

 it might appear superfluous to attempt the exact determination of 

 an element, the amount of which is known within such small limits. 

 However, as this attempt has never been made from the Greenwich 

 observations, since the time of Bradley, and as the two mural circles 

 erected there, together with the method now adopted of observing 

 alternately by reflection, afford such powerful means of detecting the 

 most minute variations in theapparent motions of the heavenly bodies, 

 the author conceived that the results of observations made under 

 such favourable circumstances might be highly acceptable to the 

 practical astronomer. V/ith this view he has undertaken the re- 

 duction of upwards of 4000 recent observations of 14 of the Green- 

 wich stars most favourably situated for determining this element, 

 those having been selected which are the most affected by aberra- 

 tion, and the least affected by refraction ; whereby the errors of ob- 

 servation have the least possible influence on the result. The final 

 result (giving equal weight to each observation) obtained by 

 Troughton's circle is 20"-505, and by Jones's circle 20"-502 ; and, 

 for the sake of round numbers, Mr. Richardson proposes to adopt 

 20" 5 as the most probable value of the constant of aberratmn. 

 This value is somewhat greater than that proposed by Dr. Brinklcy 

 and Mr. Struve, and recently adopted by this Society; but rather 

 less than the values deduced by MM. Bessel and Lindcnau. 

 Lastly, there was read a paper by Mr. James Ei)ps, upon the ni- 



clinalion 



