1810

ARBORETUM AND FRUTICETUM.

PART III-

atmosphere after the bark is removed, the injury to even the sap wood mustbe trifling if this evaporation is allowed to take place, and the hard wood cansustain no injury at all. It has also been recommended to bark oak treesbefore cutting them down, and to leave them standing for a year afterwards;but this can be attended with no other advantage than that of evaporating thesap from the outside wood more rapidly than would otherwise be the case;and this rapid evaporation is, in some seasons and situations, and especially inwarm climates, apt to produce rents and clefts in the trunk and boughs of thetrees. Nichols, who had great experience as a purveyor of oak timber forthe navy, found that, by divesting trees, before they are fully seasoned, oftheir sappy coats, the exterior parts of the wood, or heart, by exposure tothe air, suddenly contract, and shut up their pores, so as to prevent the escapeof the internal juices: hence a fermentation soon begins, and rottenness isthe certain consequence. This does not happen when timber is seasonedwith its sap on ; the outward parts of the wood not being then suddenly con-tracted, on accounted of being sheltered from the sun and wind by the coatsof sap which surround it, and the juices freely evaporating through the spongysubstance of the sap. ( Meth ., &c., p. 45.) “ Oak timber, cut into lengths, andsided (squared on the sides), soon after it is felled,” he says, “ and laidup in piles till wanted for use, is often found, in the dock-yards, very defec-tive and rotten, particularly at the heart. The annual coats of wood ofwhich trees are composed, and which encompass them like hoops, and holdthem together, are in part cut off'; and the juices flying off very quick, fre-quently cause them to split or crack, and the cracks or fissures receive thewet, which soon bring on rottenness.” (Ibid.) “ By long experience,” hecontinues, “ it is unequivocally proved, that the best way hitherto known ofkeeping or seasoning oak timber, previously to its being used in ship-building,is in a rough hewed state, with its sap on ; not only on account of applyingit, when wanted, to the most profitable uses, but by lying in the sap for two,three, or more years, it seasons gradually, and never splits or opens, as itfrequently does when the sap is taken off, by siding or cornering it when green,and laying it in piles, and whereby it receives very considerable damage, andvery often is entirely spoiled. This is never the case if it be suffered toseason in the sap : for, though the sap is certain to perish and moulder awayin a few years, let it be treated in whatever manner it may with a view toprevent its perishing, still the heart will be greatly improved by this mode oftreatment, and, I believe, will endure many years longer for it; and certainly,when it is connected, it will have the great advantage of not twisting and flyingabout, as when worked green.” ( Ibid., p. 43.) With respect to the practiceof stripping oak trees standing, Mr. Nichols is clearly of opinion that it is oflittle or no use in rendering the sap wood as good as heart wood. He relatesan instance of an oak which was stripped of its bark in the spring of 1784, andfelled in the spring of 1788. “ The tree,” he says, “ appeared, by the num-

ber of its annual coats, to have been 110 years old at the time of its beingstripped; it contained 21 coats of sap, which were in a perishing state; sothat the notion which some have entertained, that the sappy parts of oak treesbecome as hard or equal to the heart for strength and durability, by the ope-ration of stripping them standing of their bark, and letting them remain tillthey die before they are felled, is chimerical.” (p. 73.) “ The Count deBuffon has incontestably proved, by his experiments, that, by stripping oaktrees of their bark standing, and letting them remain till they die, before theyare felled, the heart, or perfect wood, thereof will be considerably increasedin strength and density; and it is also proved by experience, that the sappypart, or imperfect wood, will not be much altered thereby ; at first, and whileit is green, it will be found harder and stronger than the sap of trees felled inthe usual way; but after a little time, and as the juices evaporate and fly off,it will perish and moulder away, as the sap of oak trees always will do, letthem be treated in whatever manner they may with a view to prevent it.Every experienced ship-builder or carpenter well knows that wherever any