16 



TIMBER PINES OF THE SOUTHERN UNITED STATES. 



In any one tree the wood is lighter aiul weaker as we pass from the base tu the top. This is 

 true of every tree and of all four species. The decrease in weight and strength is most pronounced 

 in tlie first 20 feet from the stump and grows smaller upward. (See fig. 1.) 



49.6 



20 



20 30 40 



Feet from Stump. 



Fig. 1. — Diagram showing variation of weight, willi h<'ight of tree. 



50 



This great difference in weight and strength between butt and top finds explanation in the 

 relative width of the suinmerwood. Since the specific weight of the dark summcrwood band in 

 each ring is in tlirifty growth from ().()() to 1, wliile that of the springwood is only about O.JiO, the 

 relative amount of summerwood furnishes altogether the most delicate and accurate measure of 

 these differences of weight as well as strength, and licncc is the surest criterion forocular inspection 

 of quality, especially since this relation is free from the disturbing inlluence of botli resin and 

 moisture contents of the wood, so consi)icu()iis in weight determinations. 



The following figures show tlie distribution of the summerwood in a single tree of Longleaf 

 Pine, as an example of this relation: 



At Uh' Htnnip 



32 fi-i-t from wluni]i 

 87 foul froiii stumi) 



111 till- 10 ^" *''® '" ' I 



111 (uo 1 rings Nns. Average for Specific 

 rings nixi jp,, ,y ,,„ g„,j„. ,^1,;^ weight. 



to tliobiirli. 



from bark. 



Per cent. Per cent. 



37 .52 



2S 38 



IS 37 



Per cent. 

 50 

 33 

 26 



0.73 

 .59 

 .55 



