[ ase J] 
Ge Ar i Ele 
Ir the courfe found by dead reckoning be more than three points 
or 33, and lefs than five points or 56°. 
Lat. by obfervation departed from - - 52°40 N. 
Lat. by obfervation arrived at - - 54° 22'N. 
Lat. by account —) +s Bt Sats - 54° 04 
Departure wefterly 76 miles. 
Required the true difference of longitude? 
eS LE 
Wiru the latitude by obfervation 39° 18’, and latitude by ac- 
count arrived at 37° 31’, and the departure 64, find the diftance 
113 by cafe IV. of Mercator’s failing, and with this diftance 
and (atitudes by obfervation find a fecond departure 47:7 by 
cafe III. of Mercator’s failing, and with half the fum of thefe 
departures 61.8 and the latitudes by obfervation, find the true 
difference of longitude 1° 43’ by cafe IV. of Mercator’s 
failing. 
CLANS Be eli 
’ 
Ir the courfe by dead reckoning be more than five points or 56°. 
‘Lat. by obfervation departed from. - - 38° 52'N. 
Lat. by obfervation arrived at - - 40° 18’ N. 
Lat. by account - - - - - 40 — N. 
Departure wefterly by account 112 miles. 
Required the true difference of longitude? 
RULE. 
