[ 3 g 3 1 
points of divifion, which are equidiftant from T, 
draw the right lines 7 5, 8 4, 9 3, jo 2, &c. 
till they meet the former right lines, ek , di, ch , &c. 
in the points 7.5, 84, 93, 10 2, and 11 1, on 
both fides of the diameter BAD ; all which points 
are in the elliptical curve, and it is to be drawn 
through them, by hand, as in the figure. 
And right lines drawn from the center A through 
thefe points in the ellipfis, will be the true hour lines 
for a horizontal dial. 
To draw the ellipfis for a vertical fouth dial, make 
DE (in fig. 1.) the radius of the largefi; circle, and 
CF the radius of the fmalleft : the diameter of the 
former gives the tranfverfe diameter of the ellipfis, 
and that of the latter gives the conjugate : which 
being found, conftrudt the ellipfis the fame way for 
the vertical dial as above {hewn for the horizontal ; 
then draw the hour-lines in the lame manner, from 
the center of the dial, through thofe points of the 
ellipfis where the interfeclions of the crofs-lines meet 
it, as in the horizontal 5 and the thing will be done. 
Vol. LVII. 
E e e 
XXXVII. 
