MAP PROJECTIONS. 
G5 
These fables are for use in constructing tie graticules of maps, or the 
network of lines representing parallels and meridians. Suppose 
that a graticule has to be drawn comprising 4° 
of latitude and 4° of longitude between the latitudes r 
X° and X° + 4°, on any particular scale. C ms true t with ~~ ~ 
great accuracy, on a piece of tracing paper, a quadri¬ 
lateral figure, PQRS (Fig. 3), whose sides P Q = n and 
S E = p shall be the length of a degree of parallel in 
latitudes X° and X° + 1° respectively, and whose sides 
P S and Q E each = m shall be the meridional distance p--r 
between those parallels. Construct also a similar quad- Fig. 3. w 
rilateral for parallels X° 4- 3 ° and X° + 4°. 
Draw a line, H C, down the middle of the paper to represent the 
P 0 _ H 1 K 
✓ 
fit 
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f 
L 
A 
6 
h 
e 
-0 
ff 
1 
A 
B 
C D ^ 
Fig. 4. 
VOL. t. 
F 
