TKKK SURGERY AS A SUKXCE 



535 



. The cau-cs which produce cav- 

 arc almost innumerable, hut the 

 most common arc the following: im- 

 proper trimming, splitting of weak 

 crotches, gnawing hy horses, brui-es 

 caused hy lawn mowers and other im- 

 plements, the raising of the hark by 

 lightning, and. not infrequently, the 

 lacerations caused hy the climbing- 

 spnrs ti-ed hv telephone men, and, sad 

 to SHV. hv the ordinarv "iree-butcher." 

 It may safely he said that as long as 

 the hark, including, of cour-c. that on 

 the root-, remains perfectly sound and 

 whole, there will he no cavities; there- 

 fore, whenever the hark is destroyed 

 and the wood fiber is left un- 

 protected, there will be a cav- 

 ity. Kully half the work of 

 the tree surgeon is undoing 

 the damage that some one else 

 has done. One of the worst 

 troubles which he encounters 

 is the result of improper trim- 

 ming. When the average 

 man cuts otf a limb, he gen- 

 erally does so where the di- 

 ameter is the smallest, neces- 

 sarily leaving a stub ; or he 

 may leave the stub under the 

 impression that the decay will 

 be so much the slower. And 

 in those rare cases where the 

 cut is made properly, it is sel- 

 dom that he uses any precau- 

 tion to keep the wood 

 from decaying while the 

 bark is healing over the wound. 

 All cut- should be made flush 

 \\ith the limb or trunk from which 

 the branch i- taken ; but, in order to un- 

 der-tand the reason \r this, it is neces- 

 sary to take into consideration the cir- 

 culation of the tree, and the way in 

 \\hich it heal-. \- a matter of course, 

 where then- are no leaves there can he 

 no circulation; and where there is no 

 circulation there can be no healing. 

 Where the end of a limb is taken off, 

 the circulation is destroyed in that part 

 of the tree, the bark dies back to the 

 main limb or trunk, and the -tub de- 

 cay- till it falls out and leaves a cav- 

 ity. The -ame thing is true when the 



top of a tree is cut back improperly. 

 The stubs invariably decay, unless the 

 cut i- made down close to a good, live 

 branch, sloping away from that branch, 

 and protected by some method of water- 

 proofing. 



The method of treating a cavity, a- 

 devi-ed by .Mr. I )avey. i- extremely 

 comprehensive. It is based on exactly 

 the same principles as those of dentis- 

 try. l ; ir-t of all. the decayed matter i- 

 carefully removed back to good, health) 

 ti--ue. The walls of the cavity are 

 then thoroughly water-proofed and 

 studded with nails driven in, which 

 -erve to hold the filling firmly again-t 



A WATER-SHED 



Ash Tree on John D. Rockefeller Estate. Torrytown, N, Y., showing Water-shed 



around Cavity 



the -ides. Drain-tubes are always put 

 in at the bottom of the cavity, extend- 

 ing to the outside of the tree, so that 

 in case water gains entrance from any 

 unl'ore-een cause, it may be carried i 

 and the cavity remain dry. Wherever 

 the tree is (.-specially weak because of 

 the cavity, -teel brace-, both longitudi- 

 nal and transver-e, are put in for the 

 pur]>ose of reinforcement. Watcr- 

 -hed- are invariably used, to keep the 

 moi-ture out: these oui-isi ,,f deep 

 V -hapcd grooves extending from the 

 in-i'le of the top. along 1*>th side- of 

 the mouth <>f the cavity, and out at the 

 bottom, over a ledge that -lopes up- 

 ward and inward. Then the filling of 



