334 



Bulletin 256. 



It has been found that there is a tendency for portland cement to 

 contract from the wood after it dries, leaving a space between the 

 wood and the cemen t through which water and germs of decay may 

 enter. A remedy for this defect has been suggested in the use of a thick 



coat of tar, or an 

 elastic cement which 

 might be spread over 

 the surface of the 

 cavity before filling. 

 The cracking of port- 

 land cement on the 

 surface of long cavi- 

 ties, is caused by the 

 swaying of trees dur- 

 ing heavy storms, 

 and should not oc- 

 cur if the filling is 

 correctly done. 



In addition to the 

 preservation of de- 

 cayed specimens by 

 filling the cavities, 

 as above outlined, it 

 has been proposed to 

 strengthen the tree 

 by treating it as 

 shown in Fig. 257. 

 Young saplings of 

 the same species, 

 after having become 

 established as shown, 

 are grafted by ap- 

 proach to the mature 

 specimen. 



Bolting and chain- 

 ing trees. Injury frequently results from error in the method of at- 

 tempting to save broken, or to strengthen and support weak branches 

 which are otherwise healthy. The means used for supporting cracked, 

 wind-racked, and overladen branches which show a tendency to split 

 at the forks are bolting and chaining. The practice of placing iron 

 bands around large branches in order to protect them has resulted in 



Fig. 255. — The same cavity {Fig. 254) in the early stages 

 of filling; bricks are used to retain the concrete. 



