DRIVEN MACHINES 



109 



pressure of forty-five pounds will theoretically deliver 

 1,000 gallons of water. Practically, the air tank would 

 have to be loaded to a very much greater pressure to 



Figure 121. (1) Single-Gear Pump Jack. This type of jack is 

 used for wells from 20 to 40 feet deep. (2) Double-Gear, or 

 Multiple-Gear Pump Jack. This is a rather powerful jack designed 

 for deep wells or for elevating water into a high water-tank. 



secure the 1,000 gallons of water before losing the 

 elasticity of the compressed air. If one thousand gal- 

 lons of water is needed on the farm every day, then 

 the air pump would have to work about one hour each 



