J. S. Webb. — Notes on the Zodiacal Light. xlvii 



further contraction then ceases, their heat is radiated, and their gases become 

 diffused in the atmosphere. 



That these November meteors differ from the aerolites which have been 

 known to have reached the earth at various times, is clearly proved by none 

 having reached us in a solid state, notwithstanding their extraordinary 

 numbers. The presence of aerolites is also accompanied with loud reports, 

 which are absent in the case of these meteors ; surely if they were solid bodies 

 some would have reached the earth and exploded. 



Their retrograde motion might be cited as another proof. 



It is worthy of note that during the month of December the earth is 

 situated on the sun's equatorial plane, and it appears that it is near its 

 equatorial regions that all the forces emanating from the sun (motion included) 

 are principally exercised. 



Notes on the Zodiacal Light. By J. S. Webb. 

 [Read before the Otago Institute, \^th Noveniber, 1872.] 

 Having recently met with an account by Signer Respighi of some spectro- 

 scopic observations of the Zodiacal Light, I felt interested to ascertain how far 

 the facts indicated are compatible with the theory broached by Mr. Skey, in 

 the paper he read at our meeting in March last (see preceding article). Look- 

 ing for other information on the subject to assist the inquiry, I was surprised 

 to find how little was to be obtained. This being so, I have thought that I 

 should render what I have to say more interesting by prefacing it with a 

 general account of this interesting and ill-understood phenomenon. 



The account of the Zodiacal Light given by Sir John Herschel is substan- 

 tially the same as that to be found in Mr. Skey's paper. It has remained 

 unchanged throughout the successive editions of his " Outlines of Astronomy," 

 although some interesting additions to our knowledge of the subject have 

 been made in the meantime. I think Mr. Skey has been somewhat misled by 

 this, as he lays stress on the fact that the Zodiacal Light is, as stated by 

 Herschel, only visible about the vernal and autumnal equinoxes, and for a 

 few weeks before and after those dates, whilst in point of fact it is visible 

 all the year round, or nearly so. This error does not, as it appears to me, 

 invalidate Mr. Skey's theory, but a knowledge of it would probably have led 

 liim to alter his diagram (PL XIY.) somewhat, and to avoid some of the 

 remarks he has been led to make. 



After a search through all the books accessible here which were likely to 

 afford any information, I found the best account of the Zodiacal Light where 

 I least expected it, namely in the introductory notes to Keith Johnston's 

 "School Atlas of Astronomy." These notes are by Mr. J. K. Hind, and I 



