UNITED STATES DEPARTMENT OF AGRICULTURE 



JSW&*<&SL 



BULLETIN No. 556 



Contribution from the Forest Service 

 HENRY S. GRAVES, Forester 



Washington, D. C. 



PROFESSIONAL PAPER 



September 15, 191? 



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. 



Page. 



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 



