210 The Spraying of Plants. 



agitators, bases, etc., require attention, and as they are all of 

 importance, they will be briefly considered. 



Experience has led to the conclusion that no barrel spray 

 pump should have a cylinder less than 2^ inches in diameter, 

 and one with a three-inch cylinder is perhaps to be preferred. 

 This assumes that more than one nozzle is to be attached to 

 the pump, otherwise a smaller pump will answer, especially if 

 an eddy-chamber nozzle is used. But with nozzles designed for 

 heavier work, such as the "Wellhouse," the "McGowen," or the 

 " Bordeaux," the above dimensions are none too large. The 

 stroke should be at least four inches in length, and a longer one 

 would probably be better. 



Pistons may be packed with leather or with metal rings. 

 The latter are more durable, but the wear of the cylinder is 

 greater, and they are now little used in spray pumps. Leather 

 or candle-wicking is cheaper, and is at present preferred. 



The handle of a pump is a more important item than may at 

 first be supposed. It requires considerable force to move a 

 three-inch piston with the accompanying body of water, and at 

 the same time to drive the liquid through a hose and nozzle 

 with such force that it shall be broken into a spray. If the 

 handle is long, the work can be done with comparative ease. 

 By a long handle is meant one which is from 25 to 30 inches 

 from the pivot to the outer end, the distance from the pivot to 

 the piston-rod being from four to five inches additional. Full 

 allowance is here made for the length of the handle, since many 

 are made which are faulty in this respect. 



Air chambers have been almost universally regarded with 

 great favor both by the manufacturers of pumps, and by those 

 who purchase apparatus. The strong point in their favor is 

 that they cause a more uniform flow of liquid, which, to a cer- 

 tain extent, is highly desirable. The question is entirely one of 

 degree, since the presence of an air cushion unquestionably pro- 

 duces a more uniform flow. The assertion is also occasionally 

 made that greater power may be obtained by the use of an air 

 chamber, and that in consequence the spray is better and more 

 easily thrown. Having many pumps and nozzles at my dis- 

 posal, the different sides of the question have been examined. 

 Some of the chambers have been tapped and aircocks inserted. 

 Any desired amount of air could thus be displaced by the water, 



