Page:Timber and Timber Trees, Native and Foreign.djvu/211

XXVI.] growth, and hence the conversion of the faulty trees is necessarily restricted to the dimensions of flitches cut clear of the centre.

One peculiarity was noticed in the sample referred to, some of the logs had cavities or blisters, varying from one to several inches in length in the longitudinal direction of the woody layers, and spreading from 1 to 3 inches concentrically, which occurred, like the cup-shake, at various distances from the pith, and at intervals of a few feet along the line of the trunk of the tree. These cavities were partially filled with a hard secretion of resin or gum, which made up in some measure for the solidity, although it did not impart the strength which would compensate for the deficiency of the cohesive properties common to the annual layers.

From what has been stated respecting the Jarrah timber received at Woolwich, it will be readily supposed that the authorities there did not look upon it with favour, or any desire to employ it for ship-building purposes. It therefore passed to some of the minor services of the yard, and it was while under conversion for these ordinary and inferior works that I took the opportunity of making the experiments which are given in detail in Tables XCV., XCVI., and XCVII.

It is a noticeable fact in connection with the experiments, that all the specimens tried proved deficient in strength and tenacity, by breaking off suddenly with a short fracture, under an average transverse strain of about 686 lbs. weight only, or about 171.5 lbs. to the square inch of sectional area. Since the foregoing was prepared I have seen some correspondence between the Home and Colonial