UNITED STATES DEPARTMENT OF AGRICULTURE 
<s^*^3^ 
BULLETIN No. 556 
Contribution from the Forest Service 
HENRY S. GRAVES, Forester 
Washington, D. C. 
PROFESSIONAL PAPER 
September 15, 1917 
MECHANICAL PROPERTIES OF WOODS GROWN IN 
THE UNITED STATES. 
By J. A. Newlin, In Charge of Timber Tests, and Thos. R. C. Wilson, Engineer in 
Forest Products. 
CONTENTS. 
Purpose of the study 1 
Scope and method of experiments 3 
Precautions to be observed in the use of the 
data 4 
Data on green timber 7 
Data on air-dry timber 7 
Explanation of Tables 1 and 2 7 
Page. 
Explanation of Table 3 18 
Glossary 20 
Formulas used in computing 24 
Table 1 26 
Table 2 37 
List of publications and papers dealing with 
the mechanical properties of timber 46 
PURPOSE OF THE STUDY. 
This publication on the mechanical properties of wood makes 
available for general use data which will serve as a basis for (1) the 
comparison of species, (2) the choice of species for particular uses, 
and (3) the establishment of correct working stresses. 
The increasing scarcity of many species of timber which had become 
more or less standard in various wood-using industries is opening 
the field for other species. Through long use the properties which 
make the standard species valuable for a particular purpose are quite 
well understood, but it is doubtful if many manufacturers know to 
what extent other species possess those same qualities and to what 
extent they might replace the standard species. Present conditions 
will not permit long, tedious, and expensive experiments with com- 
mercial forms to establish new species in the industries; and to avoid 
this it is necessary to have definite information and data on both the 
new and the old species. With such test data at hand it is possible 
to compare the properties of a known species with those of any other. 
The possibility of substitution generally reduces to the few species 
which possess qualities approaching those previously in use. If the 
91728°— Bull. 556—17 1 
