12 A MANUAL FOR NORTHERN WOODSMEN 
carry the point occupied by the suspended end of the chain 
vertically down to or up from the mark on the ground. 
The use of plumb lines and plumbing rods for this pur¬ 
pose is well known from standard works on surveying. It 
is common woods practice to drop a pin from the head end 
of the chain, and that practice, when a pin loaded near the 
lower end is used, has been approved for United States 
land surveys. Only one such pin is required in a set, as 
after it is stuck in the ground another may be substituted 
for it. Similarly, for the rear end of the chain, when it has 
to be held above the ground, an ax held suspended beneath 
the handle, with the bit turned across the line, enables one 
to do quick and fairly accurate plumbing. For determin¬ 
ing when the chain is level, a hand level or Abney clinom¬ 
eter, such as is shown on page 93, may well be put in 
the hands of the men. There is a strong tendency on the 
part of unpracticed chainmen to hold the down-hill end of 
the chain too low. 
It is to be observed that all the above-mentioned sources 
of error work in one direction, namely, to give too large a 
valuation to the distance between two points. The young, 
school-trained man particularly, with his aspiration after 
exactness, is apt to undervalue these sources of error, and, 
in consequence, not give land enough. 
In view of all the facts and conditions, particularly be¬ 
cause of the pressure for cheapness in this class of work, 
many practical woods surveyors have concluded that it is 
best and safest not to strive after too great mechanical. 
exactness, but to make a small constant allowance at the 
rear end of the chain. On the other hand, the loose practices 
of some old woodsmen, such as letting the chain run out 
the length of a man’s arm beyond the mark, have nothing 
to be said in their defense. 
The general method of procedure in chaining, to be 
modified as circumstances may require, is as follows. 
The two chainmen will be spoken of as head and rear 
man. Commonly, the rear man is the better and more 
experienced of the two, and is in general charge. 
With one pin set at the starting point, the head man 
takes his end of the chain or tape and ten pins and steps 
