New YorK AGRICULTURAL EXPERIMENT STATION. 289 
prevent leakage of gas. The surface of the frame which rests 
against the flange is also covered with the same material, fas- 
tened on in the same manner, so that when the movable side or 
door is in place the two surfaces of felt come together. Two flat 
metal pieces projecting on each side of the base of the frame are 
for the door to rest upon and prevent it from fitting into place 
until it is forced tight against the top. Plate XLII, 0. Thirteen 
beveled buttons of oak force the door into place and press the 
felts close tegether. The buttons are made of wood bolted on 
and work on strips of tin to prevent tearing the canvas. The 
buttons are forced into place by a wooden mallet, as shown at 
Plate XLV. Metal binding handles such as used on cold-storage 
doors answer the same purpose and are somewhat easier to oper- 
ate, but cost more. 
COST OF CONSTRUCTION. 
The cost of a fumigator 10x6x6 feet should not exceed $13, 
if heavy sheeting is used to cover the frame. A good quality of 
wire net, enough to line the upper half, will cost from $2.50 to 
$4 additional. If eight-ounce duck is used the cost will reach 
about $18. 
USE OF FUMIGATOR. 
OPERATING. 
A fumigator of this model, 10x6x6 feet, is easily carried and 
operated by two men. A fumigator 12x8x8 feet, probably the 
largest size of this style that would be practical, would require 
three men. ‘The removal of one side of the fumigator prevents 
the necessity of lifting it up over the tree in order to put it in 
place. It is placed over the tree in the manner shown at Plate 
XUIMWI. At Plate XLIV the plan of setting off the charge is 
shown. The bag of cyanide is placed over the dish of acid either 
upon one of the cross braces or in the manner shown in the pic- 
ture. A string tied to the bag extends through a small hole in 
one of the upright strips of the frame. When all is ready the 
string is gently pulled from the outside and the bag falls into the 
acid. The hole is then closed with a tight-fitting wooden plug. 
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