1(5 



duck, usually "drill/' around the sheets, thus securing greater 

 dimensions with little extra weight. 



Uprights for Raising the Sheets. Those take the place of 



derricks and other cumbersome appliances used by the first 

 fumigators. Two are used, one at each side of the tree. Those 

 employed in the Board's outfit are made of straight-grained, knotless 

 pitch pine deal. This wood was the most suitable of any obtainable 

 in Cape Town. The principal piece of each is a pole, 2x4 inches in 

 section and 25 feot in length. Cross pieces, 1 x 3 in section and 6 

 feet long are bolted to each side at the bottom ; and braces of 2 x 4 

 inches, 5 feet long, also bolted in place, extend from between the 

 ends of the cross pieces to the upright piece. A guy rope, inch in 

 diameter and 35 feet long, is attached to the top of each upright. A 

 rope of ^ inch diameter and 75 feet long answers for tackle ; this 

 is passed through a fixed pulley at the top of the pole and then 

 through a movable pulley, and thence back to the top of the pole. 

 The movable pulleys are in view in the illustration. The sheet is 

 gathered four or five feet from the margin and a hitch made about 

 the gather with a short piece of rope, which, when all is ready tor 

 raising the sheet, is attached to the movable pulley. This arrange- 

 ment is superior to hitching the pulley-hook to a ring or loop sewed 

 to the sheet, as the resulting strain when the sheet is raised is far less 

 on the cloth. 



To use the uprights, one is laid at either side and the sheet dropped 

 behind the tree; the hitch is then made and the tackle attached. 

 The four men then raise the poles, and when these are vertical, two of 

 the operators steady them by means of the guy ropes, while the 

 other two raise the sheet by pulling on the tackle. When raised 

 sufficiently (see the illustration), the poles are allowed to drop slowly 

 forward, thus bringing the sheet over the tree and in position. 



Other Necessaries. The generating vessels are of lead, this 

 metal being chosen because of its durability and resistance to the 

 chemicals employed in the generation of the gas. The vessels are 

 bowl-shaped and vary from 4 inches in diameter by 2 inches in depth 

 to 8 inches in diameter by 6 inches in depth. Small, heavy, porcelain 

 dishes are used when the quantities of the chemicals are very slight. 

 Porcelain or enamel- ware dishes will answer as substitutes for lead 

 for all sizes of trees but are less economical when much work is to be 

 done because of their less durability. 



Carefully balanced scales are used for the weighing of the cyanide ; 

 the brass pans of these are protected by enamel-ware plates. 

 Measure glasses graded for fluid ounces are used for measuring the 

 water and acid required to liberate the gas. 



A tent for sheltering the supplies of chemicals, a chest in which 

 sundries are locked, half a dozen lanterns, lantern rests, spades, 

 buckets, heavy bottles for temporarily holding small quantities of the 

 acid, and air-tight tins for similar use with the cyanide, complete the 

 equipment. 



