16 



FUMIGATION FOR THE CITRUS WHITE FLY. 



sides of the octagon. The number of scjuare yards of cloth required 

 is about 18 per cent, or between one-sixth and one-fifth less than 

 for a square the sides of which are equal to the distance between 

 j3arallel sides of the octagon. 



In California 8-ounce army duck has been used almost exclusively for 

 making sheet covers, while in Cape Colony, South Africa, a No. 10 

 duck ranking in weight between 12-ounce and 15-ounce is commonly 

 used. The heavier weights are not only more durable but presumably 

 confine the gas better. A good grade of 6i-ounce drill, however, as 

 shown later by the results obtained with a bell tent of this material, 

 seems to be fully equal to the 8-ounce duck commonly used in Cali- 

 fornia. Until careful 

 experiments shall 

 have determined the 

 relative tightness of 

 various weights of 

 duck it is recom- 

 mended that sheet 

 tents be constructed 

 throughout of 8- 

 ounce duck or of 8- 

 ounce duck in combi- 

 nation with a ' ' skirt " 

 of 6i-ounce drill. 

 The author has seen 

 a sample of 8-ounce 

 drill which is no more 

 expensive than the 

 best brands of duck 



13 



i4i6|.16 



Fig. 1.— Plan for construction of octagonal sheet tent 50 feet across, 

 showing lines used in constructing octagon: A, C, side sections; B, 

 central section of fall-length strips; E, E, so-called "ends " of tent; 

 S, S, so-called "sides" of tent; R, R, reinforcements; 1-21, strips 

 of duck 29i inches wide, overlapped i an inch at the seams. 

 (Original.) 



I,., .p f c -i of this weight, but is 



evidently far superior 

 as regards tightness. 

 Anyone contemplat- 

 ing the ordering of 

 a fumigating outfit 

 should procure as many samples as possible of different brands of 

 suitable cloth and select the closest woven brand. 



The strips when cut should be overlapped three-eighths or one-half 

 inch and double stitched and all raw edges should be hemmed. In 

 calculating the number and length of strips the overlapping will 

 reduce the width of the cloth from three-fourths inch to 1 inch. As 

 an illustration of the method of calculating the length of the strips 

 used in making an octagonal tent of 8-ounce duck, 50 feet may be 

 taken as the desired size. Tliis is equal to 600 inches and the width 

 of the cloth, if 29.5 inches, will be reduced to 28.5 if overlapped one- 

 half inch at the seams. By dividing 28.5 inches into 600 inches the 



