MEASURING TREES. 31 
by any citrus grower contemplating the use of fumigation for the 
white fly, This has been thoroughly demonstrated by the experi- 
mental work conducted in the winter of 1907-8, when, as has been 
stated, approximately 4,000 trees were fumigated. 
Methods followed in experimental work. — The measurements of 
tented trees in the experiments conducted in January and February, 
1907, were made by means of a tape measure attached to a reel. In 
obtaining the distance over in each case the end of the tape was held 
in one hand while the reel was thrown over the center of the tent and 
the measurement made from ground to ground. For the purposes of 
the experiments, accuracy being desired as far as possible, measure- 
ments were made in two directions, from east to west and from north to 
south. In each case care was used to have the tape pass as nearly as 
possible over the center of the tree regardless of the highest point. Of 
72 tented trees measured in two directions, 70 per cent were found to 
vary 12 inches or less in the two measurements, 15 per cent to vary 
from 1 3 inches to 24 inches, and 1 1 per cent from 25 inches to 50 inches. 
The average variation was 12 inches and the maximum 50 inches. 
Inasmuch as it is recommended that in • using the table appended 
hereto the number in the first column next above the actual measure- 
ment (when the actual measurement is more than 6 inches above an 
even number) be selected in estimating the dosage, it is evident that in 
nearly all cases a measurement over the top of the tented tree in one 
direction, together with the circumference, wall show the dosage with 
sufficient accuracy for practical purposes. A fumigator should, how- 
ever, in using the table and knowing the measurement over in one 
direction, make allowances in case the irregular shape of the tree 
makes the single measurement over the top fall short of indicating the 
true size. 
A new scheme for obtaining measurements. — The measuring of the 
tented tree by means of the tape, as described, requires two men, 
owing to the difficulty of getting the tape over the center of the 
tree. Ordinarily it requires only one or two minutes at the most to 
obtain these measurements, but when more than a few trees are to be 
treated a simpler and quicker process is necessary. One man can 
quickly obtain the circumference by using a tape provided at the end 
with means for attaching to the tent, while he walks once around the 
tree to the starting point, unreeling the tape as needed. For attach- 
ing the tape to the tent some form of metal clamp, such as is usually 
found in stock at gentlemen's furnishing stores, is suggested. In 
fumigating on a large scale the use of a tape causes considerable 
trouble, owing to unavoidable tangling and misplacing, especially 
when used at night. One of the operators, however, should always 
estimate the circumference of the tented tree by pacing. This cannot 
be done with sufficient accuracy without considerable preliminary 
49918— Bull. 76— 08 3 
