164 E. W. Evans on the Action of Oil- Wells. 
the spontaneous flow of oil becomes slight, is to stop up the 
boring till another “head of gas,” as it is called, accumulates. 
But the stoppage should not be continued long; for instances are 
known where the gas has in consequence forced a way from its 
new channels in other directions, and found vent in other wells. 
t is not an uncommon thing for intermittent wells to throw 
out at first 300 or 400 barrels a day, or to yield in all as much 
as arrels, ‘hey sometimes run two or three years before 
exhaustion. The productiveness of the Lewellyn well on the 
if the first sunk, it is itself tapped by them. 
But some of the most marked cases of interference that are 
Again, a third well C is $. 
A B Cc 
presented by F. It finally 
descends to a fissure H, 
which communicates freely 
it and consequently 
also with D, and interferes 
both cavities above the ‘ 
mouths of the tubes. Pump- : 
ing the water out of all these simultaneously might bring the 
oil down again within reach of that tube at least which enters ab 
the highest point. A better expedient is to stop up tightly the 
space on the outside of the tube in the well C, just below the 
stream of water F. This is often effected by lowering a leather 
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