FARM MACHINERY 305 



ing boxes, but it is doubtful if the double-acting pump 

 offers much advantage. If the pump cylinder is not sub- 

 merged, it should be placed near the surface of the liquid 

 in the barrel. The air chamber should be large, as it 

 equalizes the pressure and makes the pump easier to 

 operate. 



Every barrel pump should be provided with an agitator 

 to keep the heavy spray mixtures stirred. The double-paddle 

 type is undoubtedly the most efficient type now in use, but 

 the dash agitator is in more common use and is quite efficient. 



Field Sprayers. Field sprayers differ largely in their con- 

 struction, as they are designed for spraying different crops. 

 First, in selecting such a machine, consideration should be 

 given to the truck and the tank. These should be of sub- 

 stantial and durable construction. The gearing driving the 

 pump should be of substantial construction; gears, chains 

 and sprocket^, cranks, cams, and eccentrics are used in this 

 connection, but it has not been demonstrated that any one 

 particular combination has any special advantages over any 

 other. The size of the pump must vary with the number 

 and kind of nozzles to be supplied. Some of the field ma- 

 chines used for spraying mustard and other weeds are of 

 large capacity, supplying as many as twelve nozzles and 

 covering a width of twenty feet. 



Convenience is one feature of great importance in the 

 field sprayer. The machine should be easy to fill and to 

 control. The position of the nozzles should be susceptible 

 of any adjustment which may be necessary. The pump and 

 driving mechanism should be of ready access for adjustment 

 or repairs. 



The Power Sprayer. Where there is a considerable 

 amount of orchard spraying to be done, the power sprayer 

 will be found the most economical and efficient. Man power 



