11 March, 1918. 



Vinei/a rd Sp rai/ ing. 



147 



As will Ije seen, opposite to tlie spray aperture is a larger orifice 

 through which projects a metal plug. This plug constitutes a valve 

 completely closing this orifice when the nozzle is working. On the 

 inside the plug bears a peg arranged in such a way that it can be pushed 

 right through the spray aperture, in case this should clog, by pressing 

 on the exterior part of the plug with the thumb. This not only clears 

 the spray aperture, but allows the obstruction to escape through the 

 opened valve, which immediately closes again under the pressure of the 

 liquid. A spiral spring Avas added later, which causes the valve to close 

 more tightly. This is shown in Fig. 13. This device is very con- 

 venient on all hand-directed sprays. Strainers of various types are 

 also fitted to nozzles to prevent clogging. Several excellent nozzles 

 working on the cyclone or eddy principle are now manufactured in 



Fig. 12. — Verraorel's Knapsack 

 Sprayer, ' ' Eclair. ' ' 



Fig. 13. — Venn Orel's Knapsack 

 Sprayer, ' ' Eclair ' ' — larger view 

 showing spring addition to non- 

 clogging nozzle. 



this State, into the relative merits of which it is evidently impossible 

 to go here. 



In a general way, it will be found that the higher the pressure the 

 finer and more efficient the spray; the difference between the fog-like 

 mist sent out by a nozzle working at high pressure and the few large 

 drops which it sprinkles rather than sprays if the pressure be allowed 

 to fall too low, is very striking. 



The liquid is conveyed under pressure from the reservoir to the 

 nozzle through a pipe, portion of which is flexible rubber hose and the 

 other part a metal tube. Sometimes the metal portion is fitted with an 

 interrupter, of which there are several types. On knapsack sprayers 

 interrupters are very convenient, and in the ease of staked vines they 

 permit an appreciable saving of spray liquid, by enabling the operator 



