Part II.] Troup: Fissilility of soyne Indian Woods. 
33 
The hammer-head was made hollow in order that lead could be added 
inside it should its weight have proved insufficient ; further weight, how- 
ever, was found to be unnecessary with samples of the size adopted. 
The wedges, which are made accurately to scale, are not resharpened 
on becoming worn out, but are replaced by new ones of exactly the same 
dimensions. 
In order to give free play to the wood-specimen during splitting, the 
clamping- screws are not tightened more than is necessary, and the ends 
of the clamping-socket are open in order to prevent the splitting wood 
from holding together by artificial means. 
5. — Results. 
(1) General. The Appendix contains details of all the tests made, 
the woods being arranged in order of fissibility. It will be noticed that 
in many cases the individual splitting forces often vary greatly for the 
same species, even in the case of different blocks cut fi-om one and the same 
log. These variations are not due to experimental errors, but to the fact 
that in a non- homogeneous substance like wood the relative splitting 
forces must of necessity vary, this variation being greater the less the homo- 
geneity of the wood in question ; thus conifei’ous woods, which, if free 
fro 1 knots, are among the most homogeneous of wmods, show little 
variation in the relative splitting forces of the various blocks tested, 
whereas cross-grained woods, such as Shorea rohusta, Cedrela Toona, 
Pterospernmm acerifol'%um, Ouqeinia dalbergioides and others show great 
variation, owing to the fact that the degree of inclination of the cross 
fibres varies greatly, not only in different logs of the same species, but 
even in closely adjacent parts of one and the same log. 
(2) Various Factors which affect the Fissibility of Wood. 
Among the factors which influence the fissibi- 
(a) Anatoinical Structure. , . , , • i 1 , n 
lity of wood the most important is undoubtedly 
its anatomical slnicfure, and particularly the straightness or crossness 
of grain. Woods, whether hard or soft, which have straight grain, in- 
variably split more easily than those with cross- fibres, at any rate where 
radial fission is concerned. Thus the samples of Acacia Catechu, in 
which the grain was straight, split with comparative ease, although the 
wood is one of the hardest, whereas much softer woods with cross- 
fibres, such as Garuga pinnata, Bomlax malabaricum, Gmelina arborea, 
Cedrela Toona and other fairly soft woods, required on an average more 
