34 Claypole on Natural Gas. 
And as it has been with the oil-fields of the past so will it be 
with the gas-fields of the present. They too will run out and 
fail and the tradition of their greatness will alone remain. The 
great Karg well at Findlay will cease to blow, and the greater 
roarers of Murraysville, Grapeville and Washington will also be- 
come silent. Findlay will have no more gas, and Pittsburg 
must find some substitute for its present supply of this clean 
natural fuel. 
Nor are the reasons far to seek. The geological connection 
of oil, gas, and salt water is very close. Where the strata are 
arched upward and the conditions for producing oil and gas are 
present there they accumulate, and the gas being the lightest 
rises to the top and is confined beneath the crown of the arch. 
Next comes the oil and forms a stratum below the gas. Low- 
est of all is the salt water. In such places then we have at 
three difierent levels three stores of gas, oil and brine respec- 
tively. Hence the uncertainty in the yield of a well until the 
territory has been explored. A hole sunk near the crown of 
the arch will joenetrate the upper reservoir and gas will issue. 
One sunk fai"ther down the slope of the arch will enter the oil 
layer and yield oil which is forced out by the pressure of the 
overlying gas. And a third sunk yet further from the crown 
of the arch will yield salt water. 
This, so far as we have been able to discover, is the usual 
structure of the ground where oil and gas are found in cpianti- 
ties. There may be and no doubt there are exceptions, but they 
do not invalidate the general rule. 
Now if we consider the subject a little farther, we shall see 
that as a necessar}^ consequence of this structure, when the w^ells 
have drawn off a certain part of the store of gas the oil will 
rise under the crown of the arch and eventually will reach the 
bottom of the well, when it will begin first to spurt^ then to 
spray^ and lastly to yield oil, the supply of gas at the same time 
proportionately diminishing. Later still, the continual draught 
on the oil reservoir will so far exhaust it that the brine will in 
turn rise and reach the bottom of the well. The flow of oil 
will then slowly cease and salt water will take its place, as is 
now happening in the old wells of Franklin, Pa. The last 
