2 Molesworth’s pocket-book
Chain Surveying—continued.
COMPUTATION OF ACREAGE.
Divide the area into convenient triangles, and
multiply the base of each triangle in links by halt
the perpendicular in links ; cut off 5 figures to the
right, the remaining figures will be acres; niultip y
the 5 figures so cut oft’ by 4, and again cut o o
figures, and the remainder is in roods; multiply
the 5 figures by 40, and again cut off for perches.
OBSTACLES IN BANGING SURVEY LINES.
Fig. 5.
Fig. 6.
If it be possible to see over the obstacle but not
to chain over it, lay off AC and BD (Fig. 5)
equal to each other, and at right angles to the
line, then AB = CD. If it be not possible either
to chain or see over the obstacle, lay off the lines
EF, AC, equal to each other, and at right angles
to the line (Fig. 6); range the points D H in line
with E G, and set off the lines I) B, IIG, equal to
A C and E F, and at right angles to the line E H,
then B and G are points for ranging the continua-
tion of the lines E A and A B = C D. •