10 



EYDROCYANIC-ACID GAS I I'M I (.ATI ON IX CALIFORNIA. 



3 to 4fee1 long sewed to the tent in the form of a right angle, as shown 

 in figure 7, page 1 ( .). As fumigation tents should bo pulled onto or off 

 the trees in the direction in which the strips of cloth run, the rings 

 should be so placed as to make this method of manipulation 

 possible. This is accomplished by having two rings at either end of 

 the tent and apart by about t he widt h of the average-size tree treated. 

 They should be placed from 3 to 5 feet hack from the edge, the dis- 

 tance depending on the size of the tent. A small link of chain 

 called a "jingler" is usually attached to the ring, the sole purpose 

 of which is to direct the operator to its location. By merely giving 

 the sheet a shake this simple device enables the tent pullers to 



easily locate the rings on the darkest nights. 

 Such a great strain is localized at the place 

 where the rings are attached that it is well 

 to have this part reenforced by stitching 

 on an extra thickness of cloth. The same 

 material of which the tent is constructed 

 is wry suitable. The strip used should he 3 

 or 4 feet Long. 



UK 1. 1. TENTS. 



Originally the bell, or hoop, tent was the 

 kind in use in California, and even now it en- 

 joys a limited use in some countries. This 

 tent is dome shaped, having the mouth held 

 open by a circle of J-inch gas pipe. It is 

 suited only for covering small trees. Plate I 

 illustrates the character of this tent and the 

 method of its manipulation. Experiments in 

 California have resulted in the disuse of hell 

 tents in favor of sheet tents, the latter style 

 of construction and manipulation, but also 



Fiq. :'.. Method of attaching 



hooks to (cut when COVemig 

 trees with aid of derricks: a, 

 'lent gathered around ball of 

 burlap or other suitable ob- 

 ject; /;, stout cord for attach- 

 ing ring; c, catch ring; (I, hook 

 on pulley block; e, lap link 

 or "jingler." (From Morrill.,) 



being 



not onlv easier 



more easily kept in repair. 



(JAS-PROOKINC. 



The treatment of covers with various substances to increase their 

 tightness lias been in practice to a greater or less extent since the 

 beginning of fumigation. Linseed oil was one of the first tried. 

 It renders the tents perfectly tight but greatly increases their weight. 

 Experience has proved that tents so treated are liable to burning and 

 rotting under the conditions to which they are subjected in the field. 

 Treating tents with the mucilaginous concoction resulting from 

 soaking the common cactus (Opuntia engelmanni) in water for 

 two to four days was practiced to some extent during the nineties. 

 Numerous other methods have been tried, such as painting with a 

 flexible paint; treating with glue dissolved in water; treating with 



