TREE SURGERY AS A SCIENCE 



537 



the splitting crotch, which to his skilled 

 eye often presents a serious clanger 

 which the casual observer would never 

 suspect. It is perfectly natural for the 

 weak crotch to exist in some trees ; the 

 varieties most subject to this weakness 

 are the elm, the soft maples, the lin- 

 den, and the beech. It is sometimes 

 found in other varieties, but more sel- 

 dom. It may be caused by cutting back 

 the leader and forcing out the two lat- 

 eral buds when the tree is young. Its 



heavy winds and the consequent admis- 

 sion of more water. All this while the 

 tree continues to heal on the outside, 

 making the pouch more extensive. The 

 operation continues until one of the 

 branches becomes too heavy to be 

 longer supported, and is torr off in a 

 windstorm. The method devised by 

 Mr. Davey for the treatment of such 

 cases is most effective. It consists of 

 the chain and lag-hook, VN^ith the ad- 

 dition, in serious cases, of a double- 



THE CHAIN AND LAG-HOOK SYSTEM 

 Weak Crotches Made Secure. Maple on Estate of George Lauder, Jr., Greenwich, Conn. 



treatment is complicated, and demands 

 the utmost care, especially in the ad- 

 vanced stages. When the limbs have 

 attained a sufficient size and weight, 

 the swaying in the wind causes a 

 slight splitting between the diverging 

 branches. Water is thus admitted and 

 starts the process of decay. Although 

 the tree seeks to protect itself by heal- 

 ing over the outside of the crack, it 

 merely forms a pouch for the water, 

 and the decay continues with increasing 

 rapidity, because the tree becomes 

 weaker by the repeated splitting in the 



headed bolt between the branches, and 

 bolts through the sides of the water- 

 pouch. The chains and lag-hooks are 

 used in many cases for their preventive 

 value. It is invariably the rule where 

 trees of this kind are treated, to tap 

 the pouch between the limbs, and pre- 

 serve an opening by means of one or 

 more drain-tubes. The split itself is 

 caulked in such a manner that the bark 

 will heal over it ; however, it is some- 

 times necessary when the split is very 

 bad to excavate as with other cavities 

 and fill in the same manner, although 



