WEIGHT RELATIONS. 



15 



Since, in the determination of the specific gravity above given, wood of the same i)cr cent of 

 moisture (as is the case of the vahies of strength) was not always involved, and also since the test 

 })ieces, owing to size and shape, can not perfectly represent the wood of the entire stem, the 

 following results of a special inquiry into the weight of the wood represents probably more 

 accurately the weight and with it the strength relations of the four species. 



WEIGHT RELATIONS. 

 [These data refer to the average speciiic weight for all the wood of each tree, only trees of approximately the same age being involved.] 



Average age of trees years . 



Number ot trees involved. 



Specific gravity of dry wood : 



"Weight i)er cubic foot pounds 



Relative weight 



(Transverse strength *) 



* The values of strength refer to all tests, and therefore involve trees of wide range of age and consequent^- of quality, especially those 

 of Longle.af ; involve much wood of old trees, hence the relation of weight and strength appears less distinct. 



From these results, although slightly at variance, we are justified in concluding that Cuban 

 and Longlcaf Piue are nearly alike in strength and weight and excel Loblolly and Shortleaf by 

 about i'O per cent. Of these latter, contrary to common belief, the Loblolly is the heavier and 

 sti'onger. 



The weakest material would differ from the average material in transverse strength by about 

 •2(i per cent, and in compression strength by about 30 to .'5;j per cent, e.\ce])t Cuban Pine, for which 

 the difference appears greater in transverse and smaller in compression strengtli. It must, of 

 course, not be overlooked that these figures are obtained liom full-grown trees of the virgin forest, 

 that strength varies with physical conditions of the material, and that therefore an intelligent 

 inspection of the stick is always necessary before applying the values in practice. They can only 

 represent the average conditions for a large amount of material. 



DISTRIBUTION OF WEIGHT AND STRENGTH THROUGHOUT THE TREE. 



Weight and strength of wood at different lieiijlits in the tree. 



Note. — Relative values are indicated by italic figures. 



