34 
Mr. Ivory on the Method of computing the 
APPENDIX 
TO THE PRECEDING PAPER. 
Read Nov. 7, 1811. 
Some time before the end of May last, a paper of mine was 
presented to the Royal Society, in which I entered on an exa- 
mination of a fundamental proposition in the second chapter of 
the third book of the Mecanique Celeste. About three months 
after that paper was in the possession of the Society, towards 
the middle of August, a large collection of foreign books, 
imported from the Continent, was received in London ; among 
which there were several Cahiers of the Journal de I’Ecole 
Polytechnique. In the 15th Cahier, which had been published at 
Paris in December 1809, although it did not find its way into 
this country prior to the above date, there is a short memoir 
by Lagrange on the same subject treated of in my paper: 
and in this Appendix I shall lay before the Society a short 
account of Lagrange’s memoir, pointing out what are the 
views of that celebrated mathematician in regard to the con- 
clusions obtained in my paper. 
Lagrange prefixes this title to his memoir, viz. “ Eclair- 
“ cissement d’une difficulte singuliere qui se rencontre dans 
“ le calcul de P Attraction des Spheroides tres peu diff&rens de 
i( la Sphere.” In order to avoid the explaining of new nota- 
tions I shall make use of the symbols employed in my paper. 
1 . If we put s = f~ z=zx.a\ff i__- ; the equa 
1 J J JJ Vr % ~zra .y+a 2 
