WEIGHT KELATIONS. 



15 



Siuce, ill tlie detenuiiiiitioii of the specific gravity above given, wood of the same i)er cent of 

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

 l»icces, owing to size and shape, can not perfectly represent the wood of the entire stem, the 

 loliowing results of a special in((uiry into the weight of the wood represents probably more 

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



WEIGHT RELATIONS. 



[Tlieae data refer to the average speoitic weight for all the wood of each tree, only treoB of approximately the aameage being iuvulved.] 



Average age of trees years . , 



Number ot trees involved. 



Specific gravity of dry wood 



Weight ]ier cubic foot pounds. 



Kelativft weight 



( Transverse strength *) 



Cuban. 



171 

 6 



0.63 

 39 

 100 

 (100) 



Longloaf. 



127 



22 

 0.61 



38 



97 

 (91) 



Loblolly. 



137 

 U 

 0.53 

 33 

 81 

 (84) 



Shortleaf. 



131 

 10 

 0.51 

 32 

 81 

 (77) 



*Tbe values of strength refer to all tests, and therefore involve trees of wide range of age and consequently of quality, especially those 

 of Longleaf; 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 Longleaf Pine are nearly alike in strength and weight and excel Loblolly and Shortleaf by 

 about 20 per cent. Of these latter, contrary to common belief, tlie Loblolly is the heavier and 

 stronger. 



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

 20 per cent, and in compression strength by about 30 to 35 per cent, e.\ce])t Cuban Pine, for which 

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

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

 that strength varies with physical conditions of the material, and tliat 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. 



DISTKIBUTION OP WEIGHT AND STRENGTH THBOUGHOtTT THE TREE. 



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



Note. — Kelative values are indicated by italic figures. 



