Chap. IV.] 
MISCELLANEOUS. 
147 
the branchless part of the stem loses its taper¬ 
ing form. And the stem of any tree which has 
been long bare of branches shows like the Lower 
Nile,— unvarying in size, because without a 
tributary. It will appear to the eye as large 
above as below: for, as regards the horizontal 
girthing, the head deposits equally down the 
whole extent of the bare stem below it; that is, 
though the over-deposit of growth from over¬ 
large branches on their own side of the stem 
may tend to make the stem oval instead of 
round, this will make no difference to the com¬ 
parative horizontal girthing of the tree at dif¬ 
ferent heights. And if equals are annually 
added to unequals, though the original absolute 
inequality will for ever remain the same, the 
relative inequality will annually decrease; and 
the stems of trees which have been long branch¬ 
less may be found of nearly the same girthing 
for fifty or sixty feet in height. If the yearling 
shoot is one inch in diameter, and the two-year- 
old shoot two inches in diameter, the girthing of 
one will be double that of the other: but if each 
shoot increases annually one inch in diameter, 
the proportion of their difference alters the first 
year; that is, the girthing of one, instead of 
being twice as large, is only one third larger 
