CENTRIFUGAL THROWERS. 225 



P, above. The bottom of the can is perforated like a grate with parallel 

 slits, through which the bristles act, at x, to feed out the powder and to 

 carry it around to s, where they spring from under the catch, o, to throw 

 it forth in a cloud. The broader the slits in the base of the hopper the 

 faster will it feed, and the amount to be used can be gauged by their 

 width, which will vary some for the different kinds or mixtures of pow- 

 <ler. The base, a?, of the powder-can or hopper, P, may be attached only 

 at one side, and there by a hinge, so that tlie brush, in rotating against 

 it, will cause it to shake, and thus help the feeding process. Also a stiff 

 part may be added to the brush, or its axle, to jar said base more effect- 

 nially at each rotation. 



These devices are superior to i)erforated sifters, since they do not 

 clog, while they throw a wider cloud. Also they may be used to throw 

 powder upward, but not to a great height, for in this respect they are 

 inferior to the blowers. This method is, however, applicable to x)oison- 

 ing cotton, potato-vines, &c., and worthy of being used in simple and 

 compound machines. Brushes arranged in the same way will throw a 

 spray of water, which may be fed as described elsewhere. The most 

 satisfactory of these ways is to have it drip from a spout without the 

 automatic process. 



If the elasticity of the fibers is to be used, they should be sparse and 

 turn slowly. If the throwing is to be done by the centrifugal force 

 arising from rotation (which does better than by the elasticity), the 

 velocity of rotation should be high (1,000 revolutions per minute or 

 more). The brushes rotated at 2,000 revolutions per minute made such 

 a breeze that powder and liquid could not be fed onto them at the cir- 

 cumference. This was remedied by a circular disk of sheet metal placed 

 on each end of the brush, and having the saune diameter, to prevent the 

 air from feeding into the brush by central suction at the ends. Also, 

 with high velocity, the fibers should be exceedingly scattered and of the 

 stiffest sort. By this method, stiff wires, inserted so their points stand 

 about one inch apart, form a reel, which works better than the corn- 

 bruvshes. 



Mr. L. N. Wisewell, of Ottawa, Ontario, Canada, patented a brush 

 machine in 1878 i^o. 211075), and which is illustrated in Fig. 3 of PI. 

 XXYII. As shown, it possesses a form adapting it to poisoning potato- 

 in>ects ; but with some alterations a machine on similar principles might 

 be constructed for poisoning cotton. A wheelbarrow is used as the 

 motor and carrying device. The friction wheel, *, on the spring arm, 

 <7, is held against the side of the barrow wheel, being rotated thereby, 

 and communicates its motion through its mandrel,/, pulley, J, and its 

 belt. A:, to pulley, ?, and its axis, c, bearing the arms, h &, which act as 

 agitators to keep the poison mixed in the tub-shaped reservoir. The 

 liquid flows out through a cock, ^, and its hose, ^, into the semi-cylin- 

 drical cups, r. In these cups are the rotary brushes, w, made to whirl 

 by the band, A*, driven by a rim on the barrow wheel. The whirling 

 63 CON& 15 



