[ 12 ° ] 
measurement of a degree of the meridian, and, the 
instruments being equally good, and the number of 
miles to be meafured the lame, the exadtnefs of it, to 
that of a degree of the meridian, will be in the pro- 
portion of the line of the latitude to the radius very 
nearly. 
In Tab. V. Fig. 7. let AB reprefent theaequator ; P 
the pole ; DLEF a parallel of the aequator ; PEC a 
meridian palling through the Station E j P LMN a 
meridian palling through another Hat ion M ; and let 
AMEB be a great circle cutting the meridian PEC 
at right angles in the point E. 
Then in the Spherical triangle AM N, right angled 
at N, we Shall have R : Cof. AM [Sin. ME] : : Tan. 
MAN : Co-Tan. AMN: hence I? . ’ 1 - MAN x g in _ 
ME==Co-Tan. AMN) hut Tan. MAN, being the 
Tangent of the latitude of the given place E, and 
Tan. M A N 
R 
will likewise 
therefore given, the quantity 
be given, and greater or lcfsthan unity in the propor- 
tion of the Tan. of the latitude to the R. The Co- 
Tan. therefore of the angle AMN. that is the Tan. of 
the complement of the angle AMN to 90°. will be 
greater or lefs than the Sine of the Arc ME, in the 
proportion of the Tan. of the latitude of the place, to 
the Pv. And consequently, whilffc the Arc ME is 
fmall (in which cafe the Sine, Arc, and Tangent differ 
very little from each other) the angular deviation of 
the interfe&ion of the meridian PLMN with the 
great circle AMEB, from a right angle, will contain 
more or fewer degrees, &c. than the Arc M E nearly 
in the (fame) proportion of the tan. of the latitude of 
the place to the R. 
Bv 
