346 



FORESTRY INVESXK1ATIONS U. 8. DEPARTMENT OF AGRICULTURE. 



TABLE V. TREE No. 1. 



TABLE VI. TKEE No. 2. 



TABLE VII SUMMARY op RESULTS OF TREES Nos. 54 TO 69 AND Nos. 17 TO 19. 



TIMBER PHYSICS WORK. 



The timber physics work was continued actively and the investigation extended toother kinds 

 of timber, both conifers and hard woods. In 1890 the Division was in position to announce its 

 findings with regard to the mechanical, physical, and structural study of the four principal Southern 

 pines (Circular 12). Based, as these results are, on over 2.0,000 mechanical tests and over 50,000 

 weighings and measurements, they may fairly be regarded as final, and thus avoid future discus- 

 sion and much fruitless and expensive private testing. According to this exhaustive study, the 

 Cuban and long-leaf pine rank foremost among our timber pines, and are fully 20 to 25 per cent 

 stronger than had 'previously been assumed. It also appeared that the wood of these species 

 varies in strength directly as the weight (little discrepancies being well accounted for by varia- 

 tions in resin contents, which add only to weight and not to strength); that in the same tree the 

 wood varies according to certain definite laws, being heaviest at butt, lightest in top, heavier in 

 the interior, and lighter and weakyer in the outer parts of saw-size timber; that thus the age when 

 formed, as well as the position in the tree, exercises a definite influence which is generally far 

 greater than the much-quoted influences of soil, locality, etc. In this latter respect it was clear 



