BRACING 201 



kill the bark and stop growth where they impinge 

 on the limbs, and wear their way far into the wood. 

 Any brace which wholly or partly constricts the 

 growth of a limb defeats its own purpose, for it 

 prevents by just so much the natural strengthening 

 of the limb. There is no reason why a tree should 

 have to wear corsets. 



The great point is that the nourishing sap, as 

 we have seen in the second chapter, flows down 

 the delicate cambium just beneath the bark. If 

 the cambium is killed, growth at that point ceases, 

 and decay begins. If a band is used, a strip of 

 cambium is killed which amounts to from a fourth 

 to a half of the circumference of the branch. If a 

 bolt is run clean through the limb, the nut being 

 sunk into the wood, perhaps a tenth of the circum- 

 ference of cambium will be removed, and this 

 amount will be quickly reduced as the nut is grown 

 over. No system will therefore be proposed which 

 requires the removal of any considerable amount 

 of cambium, measured on the circumference of the 

 limb. Narrow incisions into the cambium made 

 parallel to the length of the limb heal rapidly and 

 are comparatively harmless. 



Another general principle is that the brace 

 should be as high up as is possible, or, at least, as 

 is convenient. This follows from the physical law 

 of the lever and the fulcrum. A brace near the 

 crotch has to be much stronger than one which is 



