22 A MANUAL FOR NORTHERN WOODSMEN 
country where local attraction is infrequent it is sufficient 
precaution to watch the blazes and bushing back along the 
line. In any case, time is saved by setting up the com¬ 
pass approximately by the backsight before letting the 
needle go free. 
2. Try-Lines 
When two unconnected points are to be joined, it is usual 
first to run a line without spotting, a try-line so called, and 
if the desired point is not hit, to measure at right angles the 
distance between the line run and the point aimed at, fig¬ 
ure the angle of error, and rerun the line. The angle re¬ 
quired is obtained from a table of tangents. 
Thus suppose a try-line to have been run N 4° E 120 
rods or 30 chains and to have hit 32 links east of the mark 
aimed at. Dividing 32 by 3000 (the distance run in links) 
gives .0107, and the angle of which this is tangent is 
found in the table of natural tangents to be 37'. The com¬ 
pass may therefore be set N 3° 23' E, and the line rerun. 
Results near enough for most purposes may be had by 
remembering that the tangent of 1° is .0175 ( i . e., if feet in 
100, or if links per chain) and that the tangents of small 
angles are in proportion to the size of the angles. Thus 
with the case above, the tangent of 1° being .0175 and 
that of the angle required .0107, .0107 divided by .0175 
equals .61 of 1°, or 37'. 
Final Line 
5ch. 10 ch. 15 ch. 20 ch. 25 ch. 30 ch 
iTrial Line 
Diagram Showing the Method by Offset 
Or instead of using the compass to rerun the line, its 
position may be fixed by offset, that is, by measuring at 
right angles to the try-line, at different points along it, the 
distance required to place points in the desired range. For 
this purpose stakes should be left in the try-line at equal 
distances apart, say every 5 chains, and the length of each 
offset may be figured by tangents or as a simple problem 
in proportion. 
