348 Report of the Horticultural Department of the 



Hydraulic pumps. — A hydraulic spray pump consists of a pump 

 and a larger air chamber into which the spray liquid is pumped under 

 pressure. The power that immediately expels the liquid is derived 

 from the cushion of compressed air which has been formed. With 

 pressure once up a spray may be thrown for several minutes without 

 operating the pump. The pump is attached to an air chamber hav- 

 ing a capacity of from 10 to 12 gallons. A pipe extends downward 

 from the top of the air chamber to a point near the bottom, the upper 

 end being connected with the discharge pipe. The liquid is pumped 

 into the air chamber through check valves, and is forced by the com- 

 pressed air through the discharge pipe. 



This type of pumps presents certain peculiar and undesirable 

 features. Sediment is likely to settle on the valves unless there is 

 provision for agitating the liquid other than the stream as it enters 

 the chamber. Special care must be taken in packing these pumps 

 and all joints must be extra strong on account of the great pressure 

 which must be withstood. The air chamber should be provided 

 with a pressure gauge. To this class belong the Field Force Pump 

 Go's. Niagara and the Myers Hydraulic Pump (Fig. 34). 



Special features. — The air chamber of a spray pump may be 

 painted with asphaultum to prevent bordeaux mixture attacking the 

 iron and thus causing flakes to fall into the spray mixture. A per- 

 fect coating should be applied as corrosive action may begin through 

 the smallest break in the covering. Pumps with porcelain-lined 

 cylinders have been made. They have proved unsatisfactory, how- 

 ever, because it is almost impracticable to get all lumps out of the 

 lime used in making the porcelain and these soon wear the plunger. 

 We have had no opportunity of testing these pumps. 



NOZZLES. 



The subject of spray nozzles and their efficiency was investigated 

 by Professor N. O. Booth while at the Missouri Experiment Station 

 and the results are reported in Bulletin 50 of that Station. The 

 matter given under this subhead is abstracted in large part from that 

 bulletin. 



