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 actompanied 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. 4 
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 ESN 
are principally exercised. 
Notes on the Zodiacal Light. By J. S. WEBB. 
[Read before the Otago Institute, 19th November, 1872.] 
Havine recently met with an account by Signor 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 fora 
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 
him to alter his diagram (Pl. XIV.) 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. R. Hind, and I 
