TIM HER PHYSICS. 



.'531 



remarkable sinew the important influence of moisture was recognized and emphasi/ed by both 

 French and (irrman experimenters more fliaii forty years ago. 1 



These tacts were fully appreciated by the engineers of our country, as is well shown by the 

 numerous, often emphatic, approvals and recommendations of the timber-physics work undertaken 

 by the Division of Forestry, and by the eagerness with which wood consumers generally seized on 

 all information of this kind as fast as the Division of Forestry could supply the same. 



SOUTIIKKX AND NOUTHEUN OAK. 



Though fully planned before, the work in timber physics was really begun in order, to decide 

 an important controversy as to the relative value of Southern and Northern grown oak. 



A representative committee of the Carriage Builders' Association had publicly declared that 

 this important industry could not depend upon the supplies of Southern timber, as the oak grown in 

 the South lacked the. necessary qualities demanded in carriage construction. Without experiment 

 this statement could be little better than a guess,- and was doubly unwarranted, since it condemned 

 an enormous amount of material, and one produced under a great variety of conditions and by at 

 least a dozen different species of trees, involving, therefore, a complexity of problems difficult 

 enough for the careful investigator, and entirely beyond the few unsystematic observations of the 

 members of a committee on a flying trip through one of the greatest timber regions of the world. 



A number of samples were at once collected (part of them supplied by the carriage builders' 

 committee) and the fallacy of the broad statement mentioned was fully demonstrated by a short 

 series of tests and a more extensive study into structure and weight of these materials. From 

 these tests it appears that pieces of white oak from Arkansas excelled well-selected pieces from 

 Connecticut both in stiffness and endwise compression (the two most important forms of resistance). 



of testi on \orllurii mid Suulhern irhite oak madv in Washington University TMboratory, St. Louis, Mo., by Prof. 



J. IS. Johnson, 1S89. 



1 Fora more complete history sec Hulletin 6 of Division of Forestry. 

 ' See Report of the Division of Forestry. 1890. page 209. 



W. = total load at center hi pounds 

 W. L.' where L. - length in inches. 



Young's modulus of elasticity : K=rTrbTT' ? = deflection in inches. 



b. = breadth in >nclu. 

 h. _ height ill inche*. 



