58 MISSOURI BOTANICAL GARDEN BULLETIN 
Number 14 is a more expensive, but very permanent, label 
well suited for specimen trees. It consists of an oval piece of 
zine 414 x 8 inches, the letters being raised and the whole 
moulded at one time. The surface is slightly concave to fit 
the trunk of the tree, and two holes are provided for nailing 
it to the bark. This label must be inspected once in a while, 
as sometimes the expansion of the tree trunk cracks the label 
in a vertical line between the nail holes. 
The labels described above are the ones used at the Missouri 
Botanical Garden. There are other types of labels, among 
which may be mentioned painted wooden labels of various 
sizes; glazed porcelain labels with the letters burnt in; and 
flat hollow glass labels into which a written card is inserted 
and the bottom closed with a cork. 
WORK OF VOCATIONAL STUDENTS 
From time to time mention has been made in the BULLETIN 
of the training of vocational students assigned to the Mis- 
souri Botanical Garden by the United States Veterans’ Bu- 
reau. The two following articles have been prepared by two 
of the regular students and are printed as submitted, since 
it is believed that this discussion of two aspects of the work 
in the words of the men actually engaged in it gives a better 
idea of its value than any general article. 
THE USE OF EXPLOSIVES 
From an agricultural standpoint, explosives, especially the 
dynamites, are indispensable to the farmer, to the owner of 
an estate, or to the park superintendent. 
Many persons have not cared to use dynamite, because they 
thought it too hazardous, but with due care dynamite can be 
used to loosen tight subsoil, to blast holes for tree-planting, to 
loosen and break rock, to dig ditches, to blast stumps, and to 
terrace farm land. 
Last fall, in the Missouri Botanical Garden, the subsoil in 
the flower beds just south of the water-lily ponds was loos- 
ened with 20 per cent dynamite. The subsoil was found to be 
a tight impervious fire clay that became soggy in wet weather 
and extremely hard in our hot, dry summers. An inch and 
one-half auger was used, boring holes 3-314 feet deep. The 
