FIG. 39. Three specimens of oak grown under different conditions. 



The upper one is from a rapidly-grown tree, in the open, and at a low altitude ; 

 the wood is very strong, hard, and heavy (density 0-827), because there is a pre- 

 ponderance of fibres in the broad rings. The middle specimen comes from a tree 

 growing slowly in a forest at a considerable altitude ; the narrow rings have too 

 large a proportion of vessels, whence the wood is soft (density 0'691), porous, and 

 weak. The lower section is from a tree which has grown very irregularly on poor 

 soil, as shown by the variable rings ; only the parts with broad rings are good- 

 hence bad wood predominates (density 0742). (Nanquette-Boppe.) 



