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se THE WOODSMAN’S HANDBOOK. 
instead of 44 feet. With small timber, that averages 6 to 10 
inches in diameter, the error due to low measurements is practi- 
cally negligible, but with large timber it may seriously affect an 
estimate. In old spruce, careless calipering has added | inch to 
the diameters of 20 per cent of the trees. This means for every 
1,000 trees an overestimate of 8,000 feet, or on an average on spruce 
and hardwood lands about 300 feet per acre. Care also should be 
exercised to place the calipers at right angles to the axis oi the tree. 
~ is obvious that a considerable error may result if the calipers 
are placed obliquely on the trunk. When thereis a bulge or other 
normal swelling at breastheight, the measurement should be’ taken 
just above and not below the obstructions. In tropical countries, 
or with certain trees, like cypress, where many of the trees are but- 
tressed, the measurement can not be taken at breastheight, and 
special methods of grouping are used. 
In an estimate of merchantable timber only apparently sound 
marketable trees are included, and frequent errors in estimating 
come from counting unsound trees. Inexperienced or careless men 
will measure trees which may appear sound and merchantable, 
but which are really defective. Great care must be exercised to 
scrutinize each tree for signs of defect. Usually decay manifests 
itself by some external sign, such as punk knots, white resin, un- 
healthy crown, broken top, or dead limbs. A cruiser must know 
these signs. If he is working in a new country, he should associate 
with him some local woodsman who is familiar with the character 
of the timber. 
In a great deal of government work trees below the merchantable 
size and sound trees of species not yet merchantable are measured 
in connection with preparation of working plans. 
The methods of determining the volume of the trees on the strip 
surveys are described in later sections. __ 
RECORDING THE MEASUREMENTS. 
The diameter measurements are recorded in a tally-sheet note- 
book. The tally sheet is ruled in columns; the first column shows 
the diameter classes, by inches or by groups of 2 or more inches, 
and the other columns are for the various species. A special form 
of tally sheet used by the Forest Service is bound in books which 
