INSECTS, FUNGI, PLANT DISEASES, ETC. 



177 



near the middle of the gun, and by turning a crank a fan 

 is operated which blows the powder out through the tube 

 on the plant where desired. The reservoir contains about 

 one quart, and the holes in the base are adjustable, so 

 that any amount of powder may be sent out at any time 

 desired. 



Knapsack sprayers are made to hold about five gallons 



Fig. 71— Knapsack Sprayer. 



of the spraying materials, and the apparatus is so con- 

 structed as to enable the manipulator to carry the 

 machine on his shoulders. The discharge pipe should 

 enter the top of the tank, and not at the bottom. Where 

 the pipe enters the bottom it frequently becomes clogged 

 with the mixtures, thus producing continual sources of 

 annoyance. The valves are supplied with rubber balls, 



12 



