METHODS FOB OBTAINING MEASUBEMENTS \NI» DOSAGE. 
29 
(fig. 12), the distance over can be calculated by merely adding 
together the two numbers on t ho opposite sides of the lent where 
the e«le;e touches the ground. For instance, supple that on the line 
over the center of the tree 12 Is nearest the ground <>n one side and 
1.") on the other. The distance over the center of this tree would 
be the sum of these numbers, which i- 27 feet. With the lines 
graduated after this manner it makes little difference in determining 
the distance over the top o\^ 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. 
Fig. l 
A fumigation tent marked after the Morrill system. (Original.) 
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 
other-. In case of an irregularly shaped tree, by the use of this line 
the distance over can be taken in two different directions and the 
average taken for use in determining the cubic content-. In field 
work, however, this cross line is unnecessary, as measurement over 
the top in one direction i- sufficient. 
