87 



band which encircles the stem and the 

 chmber. 



A branch, as long as it is alive, does not 

 form a knot in timber, but only a cross 

 grain ; that is, as the stem increases each 

 year in diameter it encloses each year a 

 portion of the root of each of its branches, 

 and the grain of these branches forms, 

 of course, an angle, more or less acute, 

 with the grain of the stem ; but if the 

 branch dies the stem encloses each year 

 a piece of dead wood instead of living 

 wood, and as the bark then ceases to 

 run^ very frequently the bark is enclosed 

 with it. This forms a knot, instead of 

 a cross grain, in the timber ; and as the 

 dead wood is dry when it is enclosed, 

 the living wood, when sawed up, dries 

 from it. This forms a moveable knot. 

 But, besides the flaw in the timber, the 

 dead wood which is enclosed forms an 

 impediment to the course of the sap, as 



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