148 MANUAL OF GARDENING 
“It has been found that there is a tendency for portland ce- 
ment to contract from the wood after it dries, leaving a space 
between the wood and the cement through which water and 
over the surface of the 
cavity before filling. 
The cracking of port- 
land cement on the 
surface of long cavities 
162. Bridge-grafting or in- is caused by the mee 
arching from _ saplings ing of trees during 
planted about the tree. heavy storms, and 
should not occur if the filling is correctly done. 
“In addition to the preservation of decayed 
specimens by filling the cavities, as above out- 
lined, it has been proposed to strengthen the 
tree by treating it as shown in Fig. 162. Young 
saplings of the same species, after having be- 
come established as shown, are grafted by ap- 
proach to the mature specimen. 
“Tnjury frequently results from error in the 
method of attempting to save broken, or to 
strengthen and support weak branches that 
are otherwise healthy. The means used for 
supporting cracked, wind-racked, and over- 
laden branches which show a tendency to split 
at the forks are bolting and chaining. The 
germs of decay may enter. 
for this defect has been suggested in 
the use of a thick coat of tar, or an 
elastic cement which might be spread 
A remedy 
163. Faulty meth- 
ods of bracing 
a crotched tree. 
The lower meth- 
od is wholly 
wrong. The up- 
per method is 
good if the bolt- 
heads are prop- 
erly counter- 
sunk and the 
bolts tightly 
fitted; but if the 
distance _ be- 
tween the 
branches is 
great, it is bet- 
ter to have two 
bolts and join 
them by hooks, 
to allow of wind 
movements. 
practice of placing iron bands around large branches in order 
to protect them has resulted in much harm; as the tree grows and 
expands, such bands tighten, causing the bark to be broken and 
resulting after a few years in a partial girdling (Fig. 163). 
