360 Prof. Draper on inactive Tithonographic Spaces in the 
of which, notwithstanding the utter contempt Mr. Bronwin 
expresses for it, I must confess myself to be the author. The 
object of it was to show that the formule 
sausa(u+2w)..Sa(u4-2n— lo, 
ee SAWSA3 Wee SAa(2N—1)w ‘i 
cauca(u+2w).....cCau+2n—1w 
C20 = — 5 
CAZWCA4W eevee CALZN—2w 
for the forms of w objected to by Mr. Bronwin, were absolutely 
inconsistent. Suppose in the second of these w = w, cav only 
Q9r+1K + 27'K! v—1. 
n > 
hence it is only in this case that the first formule can coexist 
with the second. This is in substance the note in question, 
only I was guilty of an oversight not affecting the argument, 
which Mr. Bronwin has very correctly pointed out. I am at 
present not at all certain that he would assert that the above 
two formule can coexist; but as the second is one of Jacobi’s, 
- and his objections are founded upon the fact of one of the 
factors of the first becoming infinite or zero, for some of the 
forms of w, I do not see how they apply, except on the sup- 
position of the first formula being deducible from the second. 
In fact Mr. Bronwin has nowhere brought any objection 
against any particular step of M. Jacobi’s reasoning, and it 
will be seen on examination that there is none to be brought. 
I must still remain of the opinion that he has only proved 
that his own formule do fail when he says they fail, and that 
M. Jacobi’s are perfectly correct in every case. 
I remain, 
Yours respectfully, 
Regent’s Park, April 13, 1843. A. CayLey. 
vanishes in the particular case w = 
LXI. On anew System of inactive Tithonographic Spaces 
in the Solar Spectrum analogous to the Fixed Lines of Fraun- 
hofer. By Joun Wittiam Draper, .D., Professor of 
Chemistry in the University of New York*. 
[Illustrated by Plate III.] 
1. V HEN a beam of the sun’s light, directed horizontally 
by a heliostat, is thrown into a dark room, and 
passing through a chink with parallel sides, is received on 
the surface of a homogeneous flint glass prism, which refracts 
it at the angle of minimum deviation, and after its passage 
* Communicated by the Author. 
