28 HYDROCYANIC-ACID GAS FUMIGATION IN CALIFORNIA. 



measurements as a basis the writer has invented a formula 1 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 orunpruned 

 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. "VYoodworth (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(3tt-4) \ 

 4A2 12* / 



In this formula C equals the circumference of the tree. 



O equals the distance over the top of the tree. 



If a person works out and notes down in a chart the values of r~ and — 12 — 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. 7(), Bur. Ent., U. S. Dept. Agr., pp. 31-34, 190S. 



