CHAPTER XI. 



MACHINEEY AND DEVICES FOR THE DESTRUCTION OF 



THE WORM. 



By Prof. W. S. Barnard, Ph.D. Assistant. 



I.^SPRAY UOZZLES. 



Since most of the nozzles invented have been claimed independently 

 of insect-destroying devices, yet are applicable for throwing poison, and 

 any nozzles may be used on other machines than those they were first em- 

 ployed on, it has seemed to me advisable to treat them all in a separate 

 chapter, and to consider them in what I have found to be four natural 

 classes, viz: 1. Many-punctured nozzles; 2. Slot-nozzles; 3. Deflector 

 nozzles; and, 4. Centrifugal nozzles. The nozzles which at present 

 seem to be the best will be described under the last of these classes. 



MANY-PUNCTUEED NOZZLES. 

 [Plates XIV and XV.] 



The nozzles of this class are constructed on the dissection principle, 

 dividing the liquid into a group of small jets by forcing it through a 

 many-panctured face. 



The best nozzles of this group are such as have the tangential en- 

 trance. A removable face is of great importance ; also, the perforations 

 should be made and located, or directed, according to the principles 

 explained below. 



The old-fashioned sprinklers and sifters, with which all are familiar, 

 whether made of perforated sheet metal or wire-gauze, have generally 

 proved unpractical for administering insecticides, because of the fine 

 holes becoming clogged by the poison and other materials. To iDrevent 

 this, various stirring, shaking, and straining appliances have been com- 

 bined with them, but without as good results as are to be desired. 



The manner in which the holes are made often causes much trouble. 

 These are sometimes so cleanly drilled or punched that little or no 

 burr surrounds them ; but usually they are so punched that on one side 

 a high burr or ridge is formed around the puncture, while on the other 

 side each hole apjjears in the bottom of a funnel-shaped pit, which, if 

 pu the ipside, is excellently calculo-ted to collect and hold particles over 



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