[ 5 62 ] 
Example 3. 
Let the difference of longitude be 40°; but the 
latitudes 560 and 8o°; 
And log. 2400 ' 7 . 
+ log. conflant 3 '4 7 7 
Log. fin. 68° . . . = — 1.9671659 
S = . . . . — 1.4488876 
T (tang. 22°) = .4040262 
2109980 
Log. T m (= .61 50242) — 1.7888921 
Log. 1 ' — m (= .1830282) — 1.2625181 
Log. . . 0.5263740 = 0= — 1. 7212944 
S — D (= log. tangent 28° 6') = — 1*7275932 
wanting of the true anfwer no more than i° 4'. 
And in all cafes that can occur, the error of this 
rule will be inconfiderable. 
It is not meant, however, that it ought to take 
place of the eafier and better computation by a table 
of meridional parts : but it was thought proper to 
ffiew, by fome examples, how fafely the map itfelf 
may be depended on in the longed; voyages ; provided 
it is fufHciently large, and the neceffary rumb-lines 
are exadly drawn *. 
* See Cotefii Logometr. prop. 6. 
LXXIV. 
