f sq ] 
c’A'S EU T 
Tur Jatitudes and longitudes of two places given, to find the 
direé&t courfe and diftance between them, 
Reourrep the courfe and diftance between 
Lat. 50° 50 N. Long: 19° oo W, and 
Lat. 54° 30° N, Long. 15° 30 W, 
- Tur rule on the principles of Mercator’s failing is, 
Move the center of the femicircle perpendicularly over the 
meridional degree correfponding with the latitude departed from, 
50° 50! N, (by means of a f{quare) then move the box until the 
edge of the perpendicular cuts the meridional parts of the Jati- 
tude in 54° 30 N, and move the index until it cuts the difference 
of longitude 3° 30° on the perpendicular, and the index will 
mark the courfe 30° 10’ or N,N. E. 3 E, nearly on the femi- 
circle. 
To find the diftance failed fcrew the index to this courfe, and 
move the center of the femicircle to the proper latitude failed 
from, 50° 50’ N. andthe edge of the perpendicular to the proper 
latitude arrived at, 54° 30° N: and then the perpendicular will 
cut the diftance 254.7, miles on the index. . 
S 5 . Hoe 
