Kia. 89.—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.) 
