METHODS FOR OBTAINING MEASUREMENTS AND DOSAGE. 



29 



(fig. 12), the distance over can be calculated by merely adding 

 together the two numbers on the opposite sides of the tent where 

 the edge touches the ground. 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 determuiing 

 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. 



Fig. 12. — 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 

 others. 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 contents. In field 

 work, however, this cross line is unnecessary, as measurement over 

 the top in one direction is sufficient. 



