116 General Care of Trees 
materials, and in time perhaps causing death. Bolts should 
be used with large washers and nuts, and possibly with a 
movable chain or link attachment between the braced 
branches to allow for wind motion. 
A living brace may also be made by grafting an existing 
branch, if one can be found young enough and in proper 
position, into the branch to be braced, or vice versa. This 
‘“inerafting” is often seen in nature and answers well the 
purpose of support. 
Treatment of Street Trees. Regarding the care of street 
trees in particular, we may add a few remarks on general 
policy. 
The selection of suitable kinds — and that implies the 
removal, more or less rapidly, of unsuitable ones —is the 
first care. 
The proper spacing of the trees is the next care, and that 
implies the removal of such as are interfering with or crowd- 
ing those which are selectea to remain. The distance for 
best development should be about equal to the height of 
the tree, hence the width should vary with age, or else 
should be chosen with reference to the ultimate height of 
the tree. As a rule, thirty to forty feet will make a finally 
accepted distance. 
Trees which have become hopelessly decrepit and unsym- 
metrical should be removed to make room for better ones. 
This may be done gradually, by setting new ones before 
removing the old ones, but the effect of the older, taller 
neighbors upon the smaller new comers should be kept in 
mind, and a species should be chosen which can bear the 
shade. 
In city streets, where the natural enemies of insects, the 
birds, are largely absent, and where the health of trees is 
often precarious, and conditions are favorable to insect 
