Thinnings Pnining, and Girdling Trees. 407 



(that is, the square root beuig taken), gives 63 



2 in.; which, being multiplied into itself, pro- V^^\ J^ ^ 



duces 4 in. Then the circumference of 6 has ^'"^^/^^^^ 



been found, in such a case, to be about 6 in., 



the fourth of which is 1*5 X l'5-2'25=the 



contents of h. The circumference of c has 



been found, in such a case, to be about 5 in., 



the fourth of which is 1-25 x 1'25 = 1'5625 



the contents of c. Now, the circumference of the stem being 



8 in., one fourth of which is 2 in., which, multiplied into itself 



is 4in. ; 2*25, the contents of b, and 1-5625, the contents of c, 



added together, give 3 -8 125, which nearly equals the contents of 



a-, the difference being only '1875. 



The same correspondence may be observed if we measure any 

 of the upper branches of a tree, and also the smaller branches 

 which immediately pass into them ; and such correspondence 

 does not merely hold good where there are only two proceeding 

 branches, but also where there are three or four, or any greater 

 number. 



Hence, there is surely some probable ground for inferring 

 that, if the tree in question had been, at any time, divested of 

 either of the branches h or c, the stem would never afterwards 

 have increased more than in proportion to the increase of the 

 remaining branch ; and that, instead of having the full thickness 

 of the figure below, it would only preserve that which is shown 

 by the shaded part of the sketch^^. 64. ; in which d\s the branch 

 supposed to be pruned oif, and e the loss that 

 would have accrued to the trunk from so 6* 



doing. Of course, the same principle, if it 

 be well founded, may be applied in a propor- 

 tionable degree to the lopping off all branches, 

 whether great or small. One thing seems to 

 be quite clear; viz. that pruning, if ever )||1[ "^ / 



attended with any advantage, requires so 

 much caution and attention, that it cannot 

 be executed without considerable expense, and yet it can pro- 

 duce little or no immediate return. Then, if it be not mate- 

 rially beneficial, the expense prevents it from being profitable; and, 

 if it be injurious, the expense and the injury united must lessen 

 the ultimate value of the trees in an enormous degree. On the 

 other hand, the process of thinning generally produces some 

 return to stand against the expense ; frequently equals it ; and 

 sometimes vei*y much exceeds it. With regard to the supposed 

 advantages of pruning, in regulating the straightness and ex- 

 tent of the boles of trees, the same benefit may be obtained by a 

 due selection of the most promising stems ; and by cutting out, 

 in the process of thinning, all those which are of a contrary de- 



H H 2 



