[ 13t ] 
tude arrived at 45° 12’ laft marked by the perpendicular, and 
alfo the departure made good will be intercepted between that 
point on the perpendicular where the firft departure commenced, 
and that where the laft terminated, then the courfe S. 8° 30° W. 
the diftance 97, and the longitude arrived at 8° 8’ are found as 
in cafe IV. 
The Methods of correéting Dead Reckoning. 
CAVScr oR 
Ir the courfe found by dead reckoning be lefs than three 
points or 33°. 
Lat. by obfervation departed from - - 39° 18'N. 
Lat. by obfervation arrived at = - 37° 48'N. 
Lat. by dead reckoning arrived at - - 37°31 N. 
Courfe by dead reckoning S.S. W. 3 W. 
Departure 64 wefterly. 
Required the true difference of longitude? 
0 Saen Alia oe 
Witn the courfe S.S. W. 3 W. and latitudes by obfervation 
39° 18 and 37° 48’, find the difference of longitude 1° 9’ by 
cafe I. of Mercator’s or middle latitude failing. 
CASE 
