[ 9 ] 
Becaufe the values of the quantities yR, yS, 
y Tj depending on the different triangles ifC c, cD'd^ 
^c. are fuppofed to be no- ways affe<fted by the di- 
ftances {Bb^ C &c.) of the bafes of thofe triangles, 
from the bafe B L of the polygon, it is evident, that 
thofe values may be changed, by altering the fpecies 
of one, or more, of the faid triangles at pleafure, 
without any- ways affecting the values depending on 
the other triangles : for another polygon L 5 i a 3 4 y, 
&c. may be fo defcribed as to have all its fides, re- 
fpedtively, parallel to thofe of the former, except- 
ing only thofe (2^, y6, 78, 5>io) you would have 
to be different: fo that the whole variation in the 
VoL. 49. C feveral 
