184 University Geological Survey of Kansas. 
proportion to the space available for holding it. If I under- 
stand his paper clearly, it is comparable to gas being made in 
the old-fashioned gas-generator which could not change its 
volume no matter how much gas was manufactured within it. 
It seems to the writer that there must be certain conditions 
existing that have not yet been touched upon by geologists, and 
which must be understood before the cause of gas pressure can 
be thoroughly explained. A few of the difficulties encountered, 
should either view named above be accepted, may here be re- 
called. 
Throughout the Midcontinental field, almost without excep- 
tion, the gas pressure is proportional to depth in wells. This 
of itself is strongly favorable to the older idea of water pres- 
sure being the governing cause. Considerable pains have been 
taken to learn the initial pressure and the corresponding depth 
of wells throughout the entire area. There is not a perfect 
agreement between depth and pressure, but it is nearly so. 
Reckoning water pressure at forty-three pounds per hundred 
feet, for easy calculation, and allowing a variable depth of 
from 25 to 100 feet from the surface before reaching the per- 
manent ground-water level, there is scarcely a well in the entire 
region that does not correspond fairly well with the pressure 
exerted by a column of water for the given depth. A difficulty 
in this line, however, is met by many wells which do not ex- 
actly conform to this condition. In one instance, of somewhat 
doubtful authenticity, a well was reported over 1000 feet deep 
with a pressure of less than 250 pounds, while a well half a 
mile away was reported by the same authority as having a 
pressure of about 375 pounds at 900 feet deep. This is the only 
instance thus far noted where it was claimed that the deeper 
well had the lighter pressure, and therefore its authenticity is 
considered doubtful. But we have many cases of a variation 
from well to well of from ten to twenty-five or fifty pounds, 
which should not be expected if the pressure were entirely due 
to water pressure. It should be remembered, however, that 
there may be certain underground conditions that would inter- 
fere in the way with normal water pressure, and that such 
conditions would account for such variations. Might it not 
be true that the wells in southwestern New York and else- 
where where the water pressure is less than gas pressure that 
the latter may be increased by water having an artesian effect? 
If gas is given a pressure by ground-water and the ground- 
