[ 9I 9 3 . , 
However, the dired method of computation, by 
the abidance of the natural lines, will not be fo much 
more operofe than this compendium, as may at fill 
fight be imagined. For the arch of a grea # circ 
being drawn through C and D, f 01 ™ 1 ? t 
BCD, if the logarithmic cofine of BC or . BD , 
added to the logarithmic tangent of half the an 
CBD, and the logarithmic fine of BC oi 
added to the logarithmic fine of half this angle, 
firft fum is the logarithmic cotangent of the angle 
BCD and the fecond the logarithmic line of 
C D, the bafe of the triangle. Then, m the triangle 
A C D, from the fides, now all given, is to be com- 
puted the angle ACD, the difference between which, 
and the angle above found BCD, is the angle B C A 
when the zenith kies between the pole, and he 
great circle through C, D , but when the zenith es 
beyond that circle, the angle BCA is either the 
fum of thofe angles, or the Implement of that fum 
to a circle. And, in the laft place, if twice the loga- 
rithmic fine of half this angle, and the logarithmic 
fines of BC and AC are added together, the fum, 
after thrice the logarithm of the radius has been de- 
duced, is the logarithm of half the excefs of t le 
natural cofine of BC cn AC above the natural cofine 
of A B or the natural fine of the latitude .according 
to the trigonometrical axiom, which has been above 
referred fo ; for rad. x * veil. f. BCA is equal to 
fin. 1 BCAl’ (e). 
(0 Vide Neper. Mirif. Canon. Contaa. Edinburg. 1619, 
!>• S9- The 
