ESTIMATING GAS FOR ORCHARD WORK 79 
Asan example, Professor Woodworth cites a tree 35 
feet around and 36 feet over the top, using the o.2 per 
cent. table. Running down the circumference column 
we find that 34 feet 8 inches (the nearest to 35 inches) 
requires 8 ounces, and that the differential is 1 foot 
6 inches; that is, 35 feet requires a little over 8 ounces, 
and the difference betweeri the two measurements 
around and over the tree, 1 foot, is nearly enough to 
require another half ounce, so that 8% ounces would 
be about right. Suppose, again, the distance around 
a tree to be 4o feet, and that over the top only 35 feet; 
using the same table, we find opposite 39 feet 10 inches 
(the nearest to 4o feet) the dose 12 ounces. But the 
distance over the top is 5 feet less, and a less amount 
of cyanide will be necessary. We therefore use the 
differential (1 foot 2 inches) and deduct one-half 
ounce for each 1 foot 2 inches difference, or about 2 
ounces altogether. This leaves 10 ounces as the correct 
dose for this tree. These measurements are not sup- 
posed to be taken with every tree, but in cases of 
doubt, and occasionally to correct one’s judgment ; 
and in the case of those beginning to fumigate, whose 
judgment is not yet developed. 
The three tables following are taken from an 
excellent article on fumigation in the Rural Cal- 
fornian. Effectiveness demands accurate judgment as 
to the quantities of the chemicals to be used. This 
must necessarily vary according to the cubic space to 
be filled with gas, or, in other words, according to the 
size of the tree. ‘The tables here given, based on the 
hight and width of tree, will be found quite practicable, 
but in order to eliminate as far as possible errors of 
