Oe arial. 
eh : 
MISSOURI BOTANICAL GARDEN BULLETIN 95 
sticks should be placed on either side of the opening and 
tied at the top and bottom by a rope running around the 
trunk. A. piece of oil-cloth should then be cut to fit over 
the opening. It is tacked at the top, while the bottom is 
held in place by soil being banked against it. Beginning 
at the bottom a strip of canvas should be run from post to 
post to act as a support for the cloth. When 18 inches from 
the ground is reached the oil-cloth is turned back and into 
the form the wet concrete (1 to 4) is poured. Then a piece 
of newspaper or tar paper is laid on top to serve as an ex- 
pansion joint. The canvas strips are again run up 18 inches 
and the operation repeated until the cavity is filled. In 
order to prevent the concrete from coming out to the sur- 
face of the bark, it is necessary to remove the oil-cloth in 
3~4 hours, cut off the surplus material, bringing it back 
below the cambium, and face the filling with mortar. 
Another material which is used for fillings and which 
bids fair to supersede concrete is asphalt mixed with saw- 
dust or excelsior. Asphalt is elastic, while concrete is stiff, 
it adheres to wood perfectly, while concrete does not, and 
it is waterproof, while concrete absorbs water. Its one dis- 
advantage is the difficulty of handling. The material comes 
in the form of little bricks or in bulk. In filling, a wall 
about two inches thick is built of the asphalt by dipping 
the bricks into hot asphalt and placing them in the open- 
ing of the cavity. As an extra precaution the bricks are 
nailed to the wood and one to the other. The cavity behind 
this wall may be filled with cinders, ashes, or asphalt. The 
wall is kept from bulging out or in by wire V-shaped braces 
running from it to the back of the tree. By using a gaso- 
lene torch or hot chisel the wall may be smoothed out and 
all crevices between the bricks filled. The asphalt for fill- 
ings may be prepared by stirring sawdust in boiling asphalt, 
using three parts of sawdust to one of asphalt. ie 
Small cavities may be quickly treated by “tinning.” 
The excavation should be sala except that a led ape 
: ; bi should 
wide and 14 inch below me 8 gre should then be 
the edge of the o l 
pind ae he canted fitted. The inside of the cavity as well 
as the metal should be painted and then the erent oo 
to the ledge with galvanized nails placed one inc “ apart. 
Care should be exercised in fees the metal below the age 
bium layer, otherwise it will be torn off by the seen si 
the ingrowing bet om ree the cee leaped A _ _ 
ils, and there } 
raetal eas aes to the strain of the callus rolling over. 
