30 HYDROCYANIC-ACID GAS FUMIGATION IN CALIFORNIA. 
For instance, suppose that on the line over the center of the tree 12 
is nearest the ground on one side and 15 on the other. The distance 
over the center of this tree would be the sum of these numbers, which 
is 27 feet. With the lines graduated after this manner it makes little 
difference in determining the distance over the top of the tree whether 
or not the geometrical center of the tent is at the center of the tree, 
the single requirement being that some part of one of the graduated 
lines approximates the center of the tree. 
The two lines running parallel to this central line- should be about 
4 feet distant from it in the larger fumigating tents. The reason for 
using these auxiliary lines is, that in practice the center of the tent 
is very often pulled considerably to one side, especially in covering 
small trees. If the middle line does not fall immediately over the 
center of the tree, one of the other two lines is quite likely to do so, 
and that one should be used in obtaining the distance over. 
The cross line running at right angles to the three parallel lines also 
passes through the center of the tent and is marked like the others. 
The idea of this cross line is that in case of an irregularly shaped 
tree the distance over can be taken in two different directions and the 
average taken for use in determining the cubic contents. For experi- 
mental purposes with a few tents this line is an advantage, but in 
practical operations it is unnecessary and should never be placed on 
the tent, as measurement over the top in one direction is sufficient. 
The presence of so many lines tends to confuse the operator. 
Having calculated the volume of a tree from the two measurements, 
around and over, it is possible to dose the tree at any strength per 
unit volume desired. When the dosage has been determined the 
chemicals are measured out and placed underneath the tented trees. 
THE OLD METHOD OF PROCEDURE. 
When this investigation was started, a system of fumigation was 
used exclusive ly in which the dosage given the trees was based 
entirely on guesswork. The estimator, who ordinarily is the man in 
charge of the outfit, starts out in an orchard equipped with a blank 
schedule sheet of cross-section paper. He walks between two rows 
of trees, jotting down in the corresponding squares of the schedule 
sheet the dosage which he believes the trees should receive. This 
dosage is based on his eyesight supported by his past experience. 
If he is a careful scheduler, he will look at the trees from different 
sides before indicating the dosage, as trees are sometimes more com- 
pact on one side than on another. Less careful men set down the 
dosage for the two rows of trees while moving along as fast as they 
can walk. The writer has seen some schedulers walk through the 
orchard at a rapid pace, taking four rows at a time. 
