34. 
Indian Forest Records. 
[VoL. II 
force to split them, owing to the cross-grained structure of some of the 
blocks tested. In every case the cross-grained structure appeared on the 
radial and not on the tangential section. As evidence of the influence 
of cross-grain on the fissibility of wood^, it will be seen that Nos. 1 to 
15, that is, the most fissile woods, all have straight grain, whereas 
Nos. 52 to 61, that is, the least fissile woods, are all cross-grained. In 
general it may be said that anything which interferes with the straight- 
ness of the grain, such as the presence of knots and dormant buds, or 
obliqueness or waviness of the fibres, reduces the fissibility of the wood. 
The presence of large medullary rays is generally, and no doubt 
rightly, held to increase the fissibility of wood in a radial direction. As 
far as the present tests go, the number of specimeus tested was hardly 
sufficient to form the basis of independent conclusions on this point. Of 
the woods tested which have large medullary rays, Carallia integerrima 
split more easily in a radial than in a tangential direction, the difference 
however being small ; Casuarlna equisetifolia, on the other hand, was 
more fissile in the tangential directiou. The results in the case of the two 
oaks tested can hardly be considered conclusive. In the case of Quercus 
semecar pi folia there was no appreciable difference between the forces 
required for radial and tangential splitting ; the medullary rays, however, 
were not very conspicuous on the radial section. In the case of Q. 
dilatata fission was slightly easier in the radial than in the tangential 
direction, bat two of the specimens used for the tangential splitting test 
were knotty. 
As far as these tests show, hardness has far less Influence on the fissibi- 
lity of a wood than anatomical structure. This 
is particularly the case with straight-grained 
woods; thus Hornahum tomentosum and Acacia Catechu, both hard woods 
with straight grain, split without difficulty. In the case of cross-fibred 
woods hardness has considerable influence, for in the case of such woods 
the wedge is driven through the block by severing the cross-fibres trans- 
versely as well as by tearing them out ; this process is accomplished with 
more ease in the case of soft woods than in the case of hard woods. The 
cross-fibres of such soft woods as Bombax malabaricum, Garuga pinnata, 
and Oroxylum indicum were cut across in this way with comparative ease, 
whereas in the case of such hard cross-fibred woods as Ougeinia dalber- 
gioides, Balbergia latifolia, D. Oliveri, Pterocarpus Marsupium, Shorea 
rebusta and others, the tough hard fibres either were cut through with 
(b) Hardness. 
