a huge gasometer pressing down on the pent-up gases with its weight.
Since the Caspian Sea is eighty feet below sea level, it is probable
that the land bordering the sea has sunk since the gases and oil were
formed. And this would, in part at least, account for the enormous
pressure.

The spouting oil wells are called fountains. Some of them have yielded
two million gallons each day for months, sending up jets three or four
hundred feet high with a roar that could be heard several miles away.
Great difficulty was found at first in stopping the flow when necessary
by capping or gagging the wells, but after a time a sliding valve-cap
was invented, capable of checking the flow of the most violent well. In
order to prevent the enormous pressure from bursting the pipe and
tearing up the ground, as soon as the pipe has been sunk part way the
earth is excavated around it and the excavation is filled with cement.

[Illustration: Landing-place for commerce on the Caspian Sea]

It is said that one of these gushers threw up in a day more oil than is
produced by all the wells in the United States. One well spouted oil for
months before it could be gagged, and in the meantime flooded the
surrounding country. Millions of gallons were burned to get rid of it
and millions more were diverted into the Caspian Sea. Two wells are
reported to have thrown up in less than a month thirty million gallons
each.

At first sand is thrown out with the oil, and frequently it is ejected
with such force that a plate of iron three inches thick struck by the
stream is worn through in less than a day by this liquid sand blast.
When the wells cease spouting and it is not deemed advisable to bore
deeper, pumping is employed. Generally the oil coming from the wells is
conducted into large, carefully tamped excavations in the ground forming
ponds or lakes. In these huge reservoirs the sand and heavier parts soon
sink, making the bottom impervious. After the settling the petroleum is
either pumped into large iron tanks or sent directly to the refinery by
pipe-lines.

Since petroleum is vastly cheaper than coal, the steamers plying on the
Caspian Sea and the locomotives of many of the Russian railroads use oil
for fuel. At one time so great was the accumulation of petroleum that it
sold at the wells for a few cents a ton. A fleet of tank-steamers
conveys the oil products to the interior of Russia by the Caspian Sea
and Volga River route.

The crude pe