126 



MISCELLANEOUS. 



PT. II. 



tapering form. And the stem of any tree which has 

 been long bare of branches shows hke 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 comparative horizontal girth- 

 ing of the tree at different heights. And if equals are 

 annually added to unequals, though the original abso- 

 lute inequality will for ever remain the same, the 

 relative inequality will annually decrease ; and the 

 stems of trees which have been long branchless may 

 be found of -nearly the same girthing for 50 or 60 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 the 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 the one, instead of being twice as 

 large, is only one third larger than that of the other ; and 

 when the one girths 10 feet, the other will girth 10 feet 

 1 inch, which is in effect no difference at all. 

 There is a Agaiust the tlicory of the one vernal ascent, and 

 circulation the one autumnal descent of the sap, and in favour of 



of sap even . , . 



in winter, tlic coustaut circulatiou, or at least constant supply of 

 sap, we must consider that boughs even of considerable 



