28 TRANSACTIONS OF THE [NOV. 28, 
may accumulate in large amounts. When openings, natural 
or artificial, reach such strata, we have spouting and flowing 
wells, and the flow may continue for a very long time; but if 
the reservoirs become exhausted, or the borings become so many 
as to divide the product among a great number of openings, 
the discharge is reduced and may even cease to be profitable. 
This result has been seen in the oil-wells at Mecca, Ohio. The 
borings are made into the Berea grit, a sandstone that was found 
to be charged with petroleum. It overlies the Cleveland shale, 
which is black with carbonaceous matter, and is the evident 
source of the oil in the grit above. So great was the oil-yield at 
first, and the consequent speculation, that hundreds of wells 
were bored in close proximity; and the effect was to drain off the 
supply so rapidly that in three months all the wells were ap- 
parently exhausted, and were abandoned. But the natural pro- 
cess of renewal goes on from below, and now a small but remune- 
rative business is carried on by pumping each well for a few 
days in the year. ‘The small but regular supply thus obtained 
proves the steady continuance of production; and as neither gas 
nor oil is found or developed below the Cleveland shale, the 
latter is plainly the only possible source. 
In the Old World, we have striking examples of this continu- 
ous natural production lasting for ages. This is the case in 
China and Hindostan, and markedly on the shores of the Caspian 
Sea, where the great petroleum region of Baku has been dis- 
charging oil and gas from the ground, time out of mind. So, 
too, at Babylon, the asphalt used for mortar, in ancient times, 
is still furnished by the bitumen springs of the neighborhood. 
In all such cases, where the natural supply alone is used, it is 
practically permanent; but the rapid modern methods of pump- 
ing, and the great multiplication of wells, tend to exhaust local 
reservoirs, and outrun the rate of spontaneous renewal. 
The subject was discussed by Mr. HIDDEN and Vice-President 
HUBBARD. 
