MAINE) AGRICULTURAI, EXPERIMENT STATION. I91O. 439 



water cooled engines are said to be satisfactory — the writers 

 prefer the latter. 



Compressed air and gas sprayers: While not power sprayers 

 in the sense that the gasolene machines are, sprayers run by 

 means of compressed air or gas answer the same purpose in 

 that they provide a constant pressure without the aid of hand 

 labor or traction power. 



The compressed air type consists usually of two horizontal 

 cylinders which may be closed air tight.* One is for the liquid 

 and the other for the compressed air, and the two are connected 

 with a pipe having a shut-off. This valve is closed and air 

 pumped into the air chamber till a pressure considerably greater 

 than that desired for spraying is reached. In use the valve is 

 gradually opened allowing the pressure to escape into the cham- 

 ber containing the spray and thus force it out through the hose 

 and nozzles. Apparatus of this nature is adapted to steep, 

 rough land. Some of the objections to it are that the mixture 

 is as a rule not properly agitated, and it is necessary to purchase 

 an air-compressor to be run either by a gasolene engine or some 

 other power. 



Compressed gas machines run on the same principle as the 

 compressed air sprayers, but in this case the power is supplied 

 in relatively small cylinders of compressed gas under very high 

 pressure. These cylinders must be sent away to the factory 

 to be recharged. One of the chief advantages claimed for this 

 type is that there are no "engine troubles" or breakdowns and 

 anyone who can drive a team of horses can run them. This is 

 largely offset, however, on account of the necessity of having 

 to either keep a considerable stock of charged cylinders on 

 hand or run the risk of unexpected delays in transportation at 

 a critical time in the spraying operations. 



Agitators: Successful spraying requires that the mixture in 

 the tank is kept constantly agitated while being applied. The 

 intending purchaser should satisfy himself that the machine in 

 question is so constructed that the mixture will be well stirred 

 up from the bottom of the tank at each stroke of the pump. 



Hose extension rod and nozzles: To stand the high pressure 

 required only the best grade of hose should be purchased. This 



*One chamber may alone be used and filled parth' with liquid and 

 then the remainder with compressed air. 



