Page:Timber and Timber Trees, Native and Foreign.djvu/173

XXIV.] regard it when appropriating this timber to works of construction.

Owing to the difficulty of distinguishing the sap, many either dispute its presence altogether, or assert that if it exists it maybe safely employed the same as the sap of Lignum Vitæ; this is, however, by no means certain, as I have found that if it is placed in any damp or imperfectly ventilated situation, it decays much sooner than the heartwood; but, if used under more favourable circumstances, its durability is very great.

In connection with this question, a merchant and importer of Greenheart timber said upon one occasion, when we had a parcel under survey, that he was confident a certain log had no sapwood upon it, for if it had, it would be liable to the attack of a small worm, but that the worm would not touch the heartwood. The log referred to was accordingly tested by cutting off a thin cross section, and upon examination of the piece, there were found in it several marks or traces of the worm, which had penetrated to the depth of 2 to 3 inches; the heartwood, or duramen, had not, however, been touched. The gentleman at once admitted that, with such evidence, he would take it as conclusive that there was sap to the depth of 3 inches on the log, but that its appearance had entirely deceived him.

The case was no doubt exceptional, as the worm is very seldom seen in this wood.

Greenheart is extensively employed in ship-building for keelsons, engine-bearers, beams, shelf-pieces, &c., and for planking. It is also used for piles, and many other purposes, but its application to the domestic arts is somewhat limited by its great weight.

The strength of this wood exceeds that of most others, whether it be tried by the transverse or tensile