WOOD OF CUBAN PINE. 83 



The triaugrtlar black roughisli seeds 2J to a little over 3 Hues long, with a few faint ridges; 

 the brown, obtuse, and somewhat oblique wing (PI. XI, e,/, </), about 1 iucb in length, is deciduous 

 in germination. This species at all stages of growth can be distinguished from the Loblolly Pine 

 by the deep-green foliage, the glaucous hue of the young, tender shoots, and varying number of 

 leaves in a bundle; from the Longleaf Pine by the thinner, almost smooth, terminal buds; and in 

 the adult state, from both of these species, with which it is found frequently associated, by its 

 cones. 



THE WOOD. 



As in the Loblolly, the sapwood is wide in the young trees, measuring usually about 1 inches 

 and forming in thrifty trees fifty to seventy years old about 80 per cent of the total volume. As 

 the trees grow older, however, this preponderance of sapwood ceases, and in trees one hundred 

 and fifty to two hundred years old only 35 to 50 per cent of the total volume of the trunk was found 

 to be composed of sapwood. As in the case of the pines already mentioned, the change from sap- 

 wood to heartwood begins when the tree (or disk) is about twenty-five to thirty years old, and the 

 process is retarded as the tree (or disk) grows older, so that when any one disk is sixty years old 

 the sapwood contains about forty rings, and reaches eighty rings or more by the time the tree (or 

 disk) is two hundred years of age. As a consequence the sapwood of the disks of the main part 

 of the trunk in old trees is formed of nearly the same number of rings, and onlj- near the top a 

 marked diminution appears, while in a tree sixty j'ears old the sapwood of the stump may have 

 forty rings and that of a disk -tO feet from the ground onlj- twenty-five rings. As in other jjines, 

 the width of the sapwood is quite variable and is always greatest in young and thrifty trees. 



When green the wood of this species is too heavy to float well ; its weight varies chiefly with 

 the amount of sapwOod, and is therefore greatest in sapling timber. The sapwood itself is 

 frequently heavier than water, and where the water in the sapwood and a large amount of 

 resin in the heartwood combine, the weight of the entire disk frequently approaches 60 pounds to 

 the cubic foot. 



Kiln-dried, the wood of trees one hundred to one hundred and fifty years old was found on au 

 average to weigh about 3!) jiounds per cubic foot, thus excelling in weight even the valuable Long- 

 leaf Pine. The wood of very young trees is decidedly lighter, as is also that of very old trees, 

 the heaviest wood being formed during the age of thriftiest growth or between the twentieth and 

 eightieth year. The presence of resin in the heartwood, as conspicuous in this species as in Long- 

 leaf Pine, materially adds to the weight of the wood, so that theheartwftod of old trees is invari- 

 ably heavier than the same wood had been while in a sapwood condition. As in other pines, the 

 butt is heaviest and the top log lightest; thus in trees over one hundred and fifty years of age the 

 wood at tlie butt weighs 44 pounds per cubic foot, 37 jjounds at 38 feet, and only 32 pounds at 60 

 feet from the stump, a difl'erence amounting to over 25 per cent. This difference is greatest in the 

 young sapling and is remarkably uniform for all adult trees examined. 



In strength, as in weight, the wood of Cuban Pine excels. The following figures represent the 

 general average of a long series of experiments on wood especially collected: 



Lbs. per sq. inch. 



JIoduhLs of elasticity 2.300,000 



Transverse strength 11,900 



Compre.ssion endwise 7, 8,50 



Shearing 680 



Tension 14,300 



The average weight of the pieces tested was 49 pounds per cubic foot, the outer lighter part 

 of the old trees having largel j- been cut away in shaping the pieces, so that only heavy wood had 

 been tested. The above figures require, therefore, a reduction of about 20 per cent to represent 

 the true average strength of all the wood of entire trees. 



The amount of water contained in the fresh wood depends on the proportion of sapwood. In 

 this latter it forms about 60 per cent of the weight of fresh wood; in the heartwood only about 20 

 per cent. Accordingly, fresh logs of trees seventy years old have about 45 per cent, logs of trees 

 over one hundred and fifty years old only about 30 per cent water. The wood dries easily and 

 without great injury, even if seasoned in the dry kiln. 



