18 



.TIMBER PINES OF THE SOUTHERN UNITED STATES. 



That these statements refer only to the clear portions of eacli log, and are variably attected 

 at each whorl of knots (every 10 to 30 inches) according to thi-ir size, and also by the variable 

 amounts of resin (nit to 20 per cent of the dry weight), must be self-evident. 



Sapwood is not necessarily weaker than heurtwood, only usually the sapwood of the large- 

 sized trees we are now using is represented by the nariowringcd outer part, whieli was formed 

 during the old-age iteriod of growth, when naturally lighter and weaker wood is made; but the 

 wood formed during tin; more thrifty diameter growth of the first eighty to one hundred years — 

 sapwood at the time, changed into heartwood later— was even as sapwood the heaviest and 

 strongest. 



RANGE OF VALUES FOR WEKillT AND STRENGTH. 



Although the range of values for the individual tree of any given species varies from butt t<) 

 top, and from center to periphery by 15 to 25 per cent, and occasionally more, the deviation from 

 average valutis from one individual to another is not usually as great as has been believed; thus, 

 of 56 trees of Longleaf Pine, 42 trees varied in their average strength by less than 10 per cent 

 from the average of all 50. 



The, following table of weight (wliicli is a direct and fair indicatiou of strength), representing 



all the wood of the stem and excluding knots and other defects, gives a more perfect idea of the 



range of these values : 



liaiKje of tpvcific weight with aije (kihi-dritd u-ood). 



[To avoid fractions tlie valuer are multipUod by 100.] 



Though occaf onally some very exceptional trees occur, especially in Loblolly and Shortleaf, the 

 range on the whole is generally within remarkably narrow limits, as appears from the following 

 table : 



lUinge uf specific weight in trees of the same age apin-oximatvlg ; averages for whole trees. 

 [Spt^iilli! gravity inultiyjliid by 100 to avoid fractions.) 



From this table it would appear that single individuals of one species would approximate 

 single individuals of another species so closely that the weight distinction seems to fail, but in 

 large numbers, for instance carloads of material, the averages above given will prevail. 



INFLUENCE OF LOCALITY. 



In both the Cuban and Longleaf IMiio the locality where grown appears to have but little 

 influence on weight or strength, and there is no reason to believe that the Longleaf Pine from one 

 State is better than that I'rom any other, since such variations as are claiimd can lie foninl on any 

 40-aere lot of timber in any State. Hut with Loblolly, and still more with Shortleaf, this seems not 

 to be the case. Heing widely distributed over many localities ditVerent in soil and climate, the 

 growth ol' the Shortleaf Pine seems materially inlhieneed by location. Tiie wood from tlie Southern 

 Ooastand (iulf region and even Arkansas is generally heavier than the wood from localities (art her 

 north. Very light and line grained wood is seldom met near the southern limitof the range, while 

 it is almost the rnlt^ in jVIissoiiri, where forms resembling the Norway Pine are by no nieans rare. 

 The Loblolly, occupying both wet and dry soils, varies accordingly. 



