10 THE WOODSMAN’S HANDBOOK. 
to employ them because a satisiactory rule is not known or is 
not readily available. 
The author has endeavored to collect all the rules in use in the 
United States and Canada. Many of them are defective, and some 
are almost absurd. The log rules are compared in tables which 
give the contents of logs 12, 16, and 20 feet in length, and of all 
diameters from 6 to 60 inches. The Scribner, Doyle, and New 
Hampshire rules have been given in full, the first two being the 
ones in most common use throughout the country and the last 
being the best caliper log rule. To give them all in full would 
make the Handbook too voluminous for practical use. 
The rules are presented without discussion of their respective 
merits. However, theiroriginand modeof use have been explained 
as far as possible. As yet no sufficiently extensive study of the 
merchantable contents of logs in board feet has been made to jus- 
tify a positive statement that any single one of the log rules 
included in the Handbook is the best for general use. It is ex- 
pected that lumbermen will compare the rules and select those 
best meeting their particular needs. 
A critical consideration of the various log rules now in use will 
be given in a later bulletin of the Bureau of Forestry. 
On account of the inaccuracies of the rules and the lack of uni- 
formity in their use, the equivalents employed to convert one unit 
of measurement into another, as, for example, board feet into 
standards, or board feet into cords, vary to such an extent that 
only the figures in most common use are given. 
As yet comparatively little information has been gathered con- 
cerning the volume of standing trees, the rate of their growth, and 
the future yield of forests. But the best available figures have 
been given with the intention of adding in future editions such 
material as may then be at hand. 
The author is indebted to Mr. George Dudley Seymour for 
describing the construction and use of the instruments illustrated 
and for reviewing the manuscript, and to Mr. Roy L. Marston for 
his assistance in compiling the log rules. He desires also to 
acknowledge the courteous cooperation of Mr. John Humphrey 
and of many others who have placed at the disposal.of the Bureau 
of Forestry data regarding the measurement of timber. 
