23 



A small companion Comet was subsequently discovered by 

 Schmidt at Athens on Oct. 9th, and seen on the two following 

 days, after which it disappeared ; it was very much smaller than 

 the large Comet, and as it was only 3 or 4 degrees distant, and 

 was travelling on nearly the same track, it was probably a jjortion 

 which had been thrown off from tlie great Comet. 



It is difficult to conceive Avhat would be the effect of the 

 Sun's heat upon the Comet at perihelion, it probably would to 

 a great extent dissipate the nucleus into vapour, giving rise to the 

 remarkably bright tail. The spectrum, when first observed soon 

 after perihelion, showed the lines of sodium, and afterwards the 

 ordinary cometary bands of the hydrocarbon flame. The sodium 

 lines are now absent, while the hydrocarbon remain. On the 

 morning of the 23rd October, Avlien the Comet was remarkably 

 brilliant, the tail must have been upwards of 70 million miles in 

 length. It is of interest to know whether we shall see tliis Comet 

 again, and this at present cannot be stated as a certainty. It is 

 not unlik(4y that it will be a conspicuous object for two or tliree 

 months ; it will then be seen earlier in the night, and be more 

 conveniently placed for observation. 



Then followed a Lecture on " The Transit of A'enus," by 

 E. W. JNIauxder, Esq., F.R.A.S., Royal Observatory, Greenwich. 



The Lecturer commenced by remarking on the great import- 

 ance attaching to the determination of the Sun's distance. So long 

 as that Avas unknown, we did not know the distance, size, or 

 weight, of a single astronomical body with the exception of the 

 Moon. But if that could be ascertained, the dimensions of the 

 solar system, and of its members, were knowm at once ; and it was 

 even possible in a few cases to make a rough approximation to the 

 distances of the stars. It was the high importance of this problem 

 which made astronomers take so much interest in a Transit of 

 Venus, for this occurrence offered a means — at one time the best 

 means — for obtaining its solution. And an especial interest 

 attached to the Transit of the 6th of December, 1882, since it was 



