180 MASS. EXPERIMENT STATION BULLETIN 170. 



whereas in basal cavities if not anchored they would not, and with the 

 use of entirely independent sections the movements of cement would be 

 slightly different. 



The first to use sectional concrete in tree cavities with bolted sections 

 was probably the late city forester W. F. Gale of Springfield, about 1906. 

 Mr. Gale employed two cross bolts to each section, the sections being 

 about 20 inches long and separated in part by wire mesh. After the 

 cement had sufficiently hardened the bolts were tightened to separate 

 the sections or individual units still further. At the present time tarred 

 paper is usually employed between sections, but where there is much 

 movement this substance is hardly tliick enough, especially on the outer 

 edges, to prevent chipping. We had this feature in mind in our original 



Fig. 49. — Showing a square cavity filled with 

 cement. P, disintegrated bark above and 

 l)elow the filling; E, general path of plas- 

 tic or healing substances; F, bark cut to 

 point to accommodate tlie process of heal- 

 ing and conforming with the path of heal- 

 ing substances. 



sectional work. With the judicious use of iron bolts (which should in our 

 opinion be independent of the sections) in order to secure rigidity, the 

 sectional cement method has proved superior to the older methods of 

 filling cavities, since it has done away with much miscellaneous cracking 

 and dislodgment of fillings. 



Much improvement in the quaUty of the cement work done on trees 

 has been made witliin the last few years, especially in cement technique, 

 and some of the Portland cement surface in cavities is excellent. A 

 great deal of puttering and detail work such as thorough tamping and 

 troweling of the cement is often done in tree cavity work, especially 

 when the contract is for work by the hour. Thorough tamping and 

 troweling improve the cement, and as a result of this frequent time- 

 killing process practiced by certain unscrupulous workers some of the 

 best individual examples of cement technique may be found in trees. 

 While the sectional method of filling cavities with cement has caused 



