140 THE POTATO 



Spraying Machines. 1 A spraying outfit consists 

 of a pump, nozzle, agitator, tank rods, hose, crop-spray- 

 ing attachments, etc. They are made in various sizes, 

 and are known as knapsack, carried and worked by a 

 man; barrel, hauled by man or horse (Fig. 42), and 

 worked by manual labor; and power sprayers, in which 

 the pumping is done by gearing from the wheels, steam 



FIG. 42 A SUGGESTIVE ENGLISH SPRAYING MACHINE 

 tmphasis is laid upon coating the under surface of the leaves, and experi- 

 ments show that it is profitable to do so under British conditions. 



or gas engines, compressed air or carbon dioxid. The 

 pressure is generated in the pump; 100 to 120 pounds 

 pressure per square inch gives a much finer spray than 

 50 to 60 pounds. The power sprayers give the former, 

 the manual labor sprayers rarely exceed the latter. 

 The working parts of the pump should be of brass or 

 bronze; rubber or leather valves, or any parts that Bor- 



1 Consult Mo. Bui. 50 and (N.Y.) Geneva Bui. 243. 



