250 THE APPLE 



combine to their advantage in purchasing a power sprayer and 

 the other necessary spraying materials. 



Important points about spray pumps. The size and type of spray 

 pump selected will depend on the kind of work to be done. There 

 are so many special styles of pumps on the market that it is an easy 

 matter to find one well adapted to almost every type of spray work. 



Construction. The construction of the pump is important. The 

 most satisfactory styles of bucket, knapsack, and barrel outfits have 

 the pumping cylinder submerged in the spray liquid. This renders 

 close packing unnecessary, which lessens the friction on the pump- 

 ing cylinder and makes the work much lighter. This style of pump 

 usually has a large air chamber, which is also set within the spray 

 vessel. The air chambers which are mounted on top of the spray 

 barrels are usually made of iron, and are therefore heavy and in 

 the way, thus making the outfit much more cumbersome than those 

 in which the air chamber is submerged. 



To be most durable the working parts of a pump and all parts 

 that are submerged or come in contact with the liquid should be 

 made of brass or bronze. The nozzles, including caps, should also 

 be made of brass, and the extension rods should be lined with either 

 copper or brass pipe. Clear water should be run through the pump 

 after each day's spraying, especially if lime-sulphur is used. 



The pump should have sufficient capacity to do the required 

 amount of work with ease. To produce a good spray, it is neces- 

 sary to have high pressure, and here lies the secret of the value 

 of the modern power sprayers. 



Agitation. One of the most important points in a spray outfit 

 is the means used for agitating the liquid. Good agitation may in- 

 crease the effectiveness of the spray from 20 to 50 per cent. The 

 best barrel and power outfits secure this by a direct attachment to 

 the pump. A stream of spray liquid returning into the tank does 

 not usually give good agitation. Some form of paddle agitation, 

 either whirling or dashing, is preferable. 



Straining. The spray machine should be equipped with a good 

 strainer, such as the Stewart strainer, in which the liquid passes 

 upward through the screen. Other types of sloping screen are 

 good. The screen, no matter how made, should be of heavy brass 

 cloth and have at least 14 wires to the inch. Wire cloth having 



