10 A MANUAL FOR NORTHERN WOODSMEN 
by opening of the joints. Chains have every tenth link 
marked by a brass tag, and these tags have one, two, three, 
etc., teeth, so that the number of links may be readily and 
accurately counted. 
Chains change in length by use. The links may be bent 
and the chain thus shortened, a matter which can readily 
be adjusted by hammering; but more commonly a chain 
increases in length from flattening of the links and wear 
in the numerous joints. This may be corrected to a limited 
extent by turning up the nuts which hold the handles. 
Further effect may be had by taking out one or more of the 
rings which connect the links, or better still, by hammering 
each link while it is held in a vise, and so distributing the 
correction. 
The chain is so liable to change in length that provision 
should be made for testing it frequently. An unused tape, 
known to be of true length, kept at home or only taken 
off on long jobs, is the best and most convenient safe¬ 
guard. 
2 . The Tape 
Steel tapes are in wide use for general surveying, but 
not usually among woodsmen because of their liability to 
breakage. They have, however, distinct advantages. 
They are light, so as to be leveled readily when measure¬ 
ment is being made on a slope. They do not stretch. 
There are no links to get kinked and so cause a false 
measure. A tape for field use should be made of steel 
ribbon from ^ to J inch wide and No. 30 to 32 thick. 
Wider and thinner tapes are a nuisance in woods 
conditions. 
Tapes are made of any length and graduated to suit the 
work for which they are designed. One 66 or 33 feet long, 
graduated to links, will best suit the needs of the timber 
land surveyor. 
Some precaution must be taken with steel tapes. When 
in use, they should be kept out at full length and never be 
doubled on themselves, for, if doubled, they are easily 
kinked and broken. When done up, they should be wiped 
clean and dry, and so cared for as to prevent rusting. A 
