[ 15 + 3 
clrcumftance is much greater than I was at firfl aware 
of. I owe this better information entirely to the re- 
vifal of Dr. Stewart’s Theorems, not to any thing 
that has been written upon the fubjed by others. 1 
find that if I increafe the mean quantity of the fun’s 
difturbing force, as determined by Dr. Stewart in the 
9th propofition of his Supplemental Trad:, and by 
myfdf, in my former paper, by _^J4__^th part of it- 
felf, I obtain, by my own method of computation, 
9" 3' 394. for the Sun’s mean horizontal parallax ; 
which feems to be fo nearly the mean of the quantities 
of the parallax deduced from the beft obfervations of 
the tranfitof 1761, that it would be ridiculous to fet 
up, any longer, the conclufions of this theory in op- 
pofition to obfervation. It is much more probable 
that the theory fhould err in fo fmall a matter as 
.j^^th of the Sun’s difturbing force, than that 
obfervation (hould err in more than .1, that is nearly in ^ 
of the whole quantity in queftion, 1 beg tlie favom: 
of you to communicate this to the Society^ 
I have the honour to be, Sir^. 
Your raoft obedienti, 
and moft humble fervant„ 
Samuel Horfley 
Oxford, May 
1769. 
XX. Mi'ixoro^ 
