28 HYDROCYANIC-ACID GAS FUMIGATION IN CALIFORNIA. 
measurements as a basis the writer has invented a formula x by 
means of which the cubic contents of a tree may be computed. 
To avoid computation work in the field, in so far as possible, the 
writer has formulated a table approximating the cubic contents of 
trees of different dimensions, which is sufficiently extensive to include 
any citrus tree in southern California. During this investigation no 
tree has been found whose dimensions did not fall within the limits 
given in this table. The distance around and over a given tree being 
known, the table will show the approximate cubic contents of the 
tented tree. The dosage can then be applied in proportion to the 
contents and at any strength desired. 
A lemon tree, after being pruned, is flat on the top. Therefore 
the geometrical figure which is applicable to an orange or unp rimed 
lemon tree can not be considered as applicable to a pruned or flat- 
topped lemon tree. The figure which approximates the latter is a 
cylinder. Now it so happens that the contents of a cylinder having 
certain dimensions over its top and around its bottom are almost 
the same as for a figure of the same dimensions composed of a cyl- 
inder surmounted by a hemisphere. This is a great advantage, for 
the schedule of dosage proposed for orange trees may also be used 
for all lemon trees, thus obviating the necessity of preparing two 
different schedules. 
SECURING THE MEASUREMENTS AROUND AND OVER. 
The distance around the bottom of a tent is easily secured by the 
use of a tapeline, or by pacing. The distance over the top, however, 
was much more difficult to determine until Dr. A. W. Morrill, 2 in 
the course of his work for the Bureau of Entomology against the citrus 
white fly (Aleyrodes citri R. & H.) in Florida, invented a method of 
marking tents for this purpose. The Morrill method renders the 
securing of the distance over the top of the tent as easy as that 
around the bottom. 
1 Prof. Woodworth (Bui. 152, Univ. of Cal. Agr. Exp. Sta., p. 5, 1903) was not only the first to suggest the 
measurements around the bottom and over the top of tented trees, but also was the first to propose a for- 
mula for obtaining the contents of tented trees based on a knowledge of these distances. An analysis of 
this formula during the early part of the writer's field work proved that it was inaccurate, thus necessitat- 
ing the determination of a new formula. The writer has worked out a formula based on the two measure- 
ments above mentioned. It is as follows: 
C2/Q_ C(3r-4) \ 
4A2 12^ ) 
In this formula C equals the circumference of the tree. 
O equals the distance over the top of the tree. 
Q2 C(3; 4) 
If a person works out and notes down in a chart the values of r- and — ^ for different values -of C of 
which he is apt to make common use, it is possible by its use in connection with the formula to determine 
the contents of trees with fair rapidity. 
2 Bui. 76, Bur. Ent., U. S. Dept. Agr., pp. 31-34, 1908. 
