TIMBER. 



123 



elms, acquire thicker and longer stem, in closer or- 

 der, in a given time. In this country, in rich warm 

 situations, this is visible in some degree, both as re- 

 gards quantity of timber and quickness of growth, 

 compared with pines. It would be difficult to state 

 the comparative quickness of growth of the various 

 timber trees, as so much depends on soil, situation, 

 and treatment ; it also varies considerably at differ- 

 ent stages of their growth. It is well known, that 

 in proper soil, black Italian poplar, Salix alba, and 

 red wood willow, exceed all others. 



As, for naval use, it is not the quickness of growth 

 and bulk of the timber altogether, but of the matured 

 timber alone, which is of consequence — we give a 

 view of the number of growths or annual circles of 

 sap-wood (the useless part), which the main stems of 

 several kinds of trees presented. Most of those we 

 examined had a greater number of sap-layers near 

 the top than at a few feet above ground, and the vi- 

 gorous branches had generally more than the stem 

 immediately adjacent to them ; the branches with 

 least vigour had fewest sap circles. 



