April, '11] BALL: OKCHARD SPRAYING APPARATL'S 185 



within the limits of their capacity. The double-acting hand-power 

 pumps are usually efficient instruments, provided the air chamber 

 is of sufficient size. Many of the present models are equipped with 

 air chambers too small to equalize pressures above 200 pounds. In 

 the power outfits much loss has been occasioned through lack of 

 rigidity in the construction of the frames, which often yield under 

 trying conditions to which they are subjected in orchard work. Many 

 of these outfits are put out with too small air chambers for the pres- 

 sure that they are capable of developing. Provision should be made 

 in all outfits expecting to handle pressures above 100 pounds whereby 

 air can be forced into the chamber under pressure before pumping of 

 liquids is commenced, thus giving a much larger air cushion than can 

 be obtained where liquid is forced into the air chamber and only a 

 small amount of air is compressed. This problem has been solved 

 by different manufacturers in different ways and should be a require- 

 ment of all outfits in the future. 



One of the most annoying features of present pump construction is 

 the Hability of trouble with the relief valve. The constant friction 

 of spraying solutions passing through the valves soon wear the delicate 

 parts until it is impossible to make adjustments and still allow of 

 sufficient escape to handle all the liquid when the nozzles are shut off. 

 Unless there is sufficient room to handle the entire capacity of the 

 pump with ease, the pressure runs up when the nozzles are turned off 

 and the pump is thereby subjected to severe and useless strain which 

 only results in more rapid wearing of the affected parts. Many devices 

 have been designed to overcome this objection and some of them are 

 fairly successful. A device on exhibition at the recent tests at Council 

 Bluffs, in which the entire matter was obviated by regulating the 

 amount of hquid taken in through the suction pipe and doing away 

 with the escape valve, suggests the possibility of entirely obviating 

 these defects in the future. While probably improvements could be 

 made on the present apparatus, the principle of shutting off the hquid 

 when the nozzles are cut off rather than providing for an escape is the 

 correct one, thus obviating almost all unnecessary wear on the engine 

 and pump. In this connection, it has already been suggested by dif- 

 ferent workers that the outfits of the future will probably not pass the 

 sprajdng liquid through the pump at all. One of the most serious 

 drawbacks to efficiency of spraying apparatus at the present time 

 is the necessity of fitting them to resist the corrosion of the different 

 spraying compounds. If the necessity of passing these through the 

 pump is obviated, it will probably both cheapen and simplify pump 

 construction. The prime requisites of successful orchard work are 

 unlimited power and constant pressure, and, on this account, spray- 



