224 
PRUNING AND THINNING. 
[Part IV. 
A living branch 
forms a cross¬ 
grain ; when 
it dies, an united 
knot. What 
is afterwards 
inclosed, a dis¬ 
united'j mov¬ 
able knot. 
of circumstances,—the price of labour, of the 
faggots, of the timber, &c. &c. 
A branch, as long as it is alive, does notTorm 
a knot in timber, but only a cross-grain, that 
is, as the stem increases each year in girthing, it 
incloses each year a portion of the root of each 
of its branches; and the grain of these branches 
forms, of course, an angle more or less acute 
with the grain of the stem. But this cross-grain 
is united grain for grain ; that is, growth for 
growth with the grain and growth of the stem. 
And if the tree is cut while the branch is alive, 
the branch forms no knot, but only a cross¬ 
grain. If the branch dies while the tree is 
alive, the cross-grain dries, and becomes an 
united knot. Afterwards the stem incloses, each 
year, a piece of disunited dead wood instead of 
living wood, which is united to it. This forms a 
disunited knot, instead of an united knot, in the 
timber; and as the dead wood is dry when it 
is inclosed, the living wood, when sawed up, 
dries from it. This forms a movable knot. 
The bark ceases to run when dead, and is fre¬ 
quently inclosed with the dead branch. This, 
and afterwards rottenness of the outside of 
branches, increase the disunion of knots from 
the timber. But, besides the flaw in the timber, 
