ESTIMATING GAS FOR ORCHARD WORK 79 



As an example, Professor Woodworth cites a tree 35 

 feet around and 36 feet over the top, using the 0.2 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 i foot 

 6 inches; that is, 35 feet requires a little over 8 ounces, 

 and the difference between the two measurements 

 around and over the tree, i foot, is nearly enough to 

 require another half ounce, so that S}4 ounces would 

 be about right. Suppose, again, the distance around 

 a tree to be 40 feet, and that over the top only 35 feet; 

 using the same table, we find opposite 39 feet 10 inches 

 (the nearest to 40 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 (i foot 2 inches) and deduct one-half 

 ounce for each i 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 Cali- 

 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 



