58 



The situation of such branches will 

 make a considerable difference, as to the 

 quantity of obstruction. When several 

 large ones are placed at or about the same 

 height, and so as nearly to inclose the 

 stem, it is obvious, that they must so far 

 obstruct the sap, that the principal leader 

 will have only a small proportion, and 

 consequently can grow but slowly ; though 

 in young trees, and in soft woods, the da- 

 mage will ^be trifling, in comparison of 

 that where the case is reversed*. 



Having seen that a tree, tolerably free 

 from knots, is likely to give us the greatest 

 general height and thickness, the deduc- 

 tion is plain, it must give us likewise the 

 greatest length of stem : and all will admit 

 that to be an essential point in the value 



» The sap-vessels in firs, are larger than in any other 

 wood we have noticed ; a circumstance that seems to 

 account for their heads growing freely, though their 

 stems are beset with very numerous branches. 



