208 



Fissility and Interlockedness. 



Schlich (Fisher), v, 39, has a special section devoted to "Fissility," or 

 " Fissibility," as he calls it. 



By the fissibility of wood is meant the property it possesses of being split by a wedge driven into 

 it in the direction of the fibres. Fissibility is clearly a form of hardness. . . . Branch and rootwood, 

 owing to twist. >d knotty structure is harder to split than stem wood, and no part of a tree is harder to split 

 than the stump, where th • tap and side-roots unite to form the bole. Trees with twisted fibre are specially 

 hard to split, and it is found that those twisting from left to right (against the sun's apparent course) are 

 harder to split than those twisting in the opposite direction. The structure of the medullary rays has 

 very great influence on the fissibility of a wood, for they are in the plane in which the principal splitting 

 action lies, so that (trees) with large rays are easily split. 



In addition to this factor of structure, he deals with Elasticity and Flexibility of 

 Fibre. Moisture, &c. Locality and Mode of Growth, all in relation to Fissibility. 



Tin isc tint Iters which are converted by splitters into rails, shingles, and palings 

 may be fairly enumerated as fissile. As a rule, species producing such timbers grow 

 in sheltered valleys with good soil and drainage, and good cultural conditions generally, 

 so as to encourage straight, rapid growth. The timber-getter, as a rule, knows his 

 species by experience, and he selects individuals by reason of their absence of twist, 

 usually i il ivious in the bark to the trained eye. A simple guide will be the list of uses to 

 which timbers are put and which presuppose fissility, in my " Notes on the Commercial 

 Timbers of New St tut It Wales" (Third Edition). 



Amongst Eucalypts, t lie Stringyharks have a fair degree of fissility, to which 

 may be added the Mountain Ashes*(.Zs. regncms and E. gigemtea), which are more fissile 

 still. But very many species are worked up by splitters for one use and another. 

 Fissility enters somewhat into the classification submitted at p. 142, Part LIU. 



Notice the admirably depicted shearing tests in Plates 60-64 of Julius, 1906 (a). 

 The following also is a measure of fissility :— 



Tests to determine the holding power of dog spikes in sleepers were made with both old and new 

 sleepers the old Bleepers being drawn from the " road " by withdrawing two out of the four spikes, thus 

 allowing the sleeper to be removed without disturbing the remaining two spikes. 



The-, were then " pulled out" by means of the apparatus shown in Plate 2G, the " pull " required 



-t;irt " the spike being recorded, as also the size and type of spike. New holes were bored in the 



''old" sleepers and tie spikes redriven, to be again pulled "tit in order to determine the holding power 



of the '■ u-e | " deepei upon the freshly-driven spibs. Similar te*is were also made upon new sleepers. 



All of the -pike, wen mare, and, with tl icception of several of the oldest sleepers were 



of ti ■ i rd patt< rn marked Q, on Hate 26, and had I n driven into holes bored with a g-inch auger. 



V Timl.e, Ti 1906 ' -. <;. \. Julius, p. 11.) 



Photographs illustrating fractures, which are a measure of fissility, can be seen, 

 qoI only in the works of Julius, but also in those of Professor Warren, A. 0. Green, 

 Nangle, and many others. 



