strata of coarse sandstone, but we are not
quite sure how it happened to be there. The sand which formed these
strata was deposited by water ages and ages ago--we are certain of
that. Another thing that we are certain of is that where the strata
lie flat, there is no oil. Hot substances become smaller as they cool;
and as the earth grew cooler, it became smaller. The crust of the
earth wrinkled as the skin of an apple does when it dries. In the tops
of these great sandstone wrinkles there is often gas; and below the
gas is the place where oil is found. There is no use in looking for
petroleum where the folds of the strata are very sharp, because in
that case the strata crack and let the oil flow away. It is not in
pools, but the porous stone holds it just as a sponge holds water. If
you drop a little oil upon a stone even much less porous than
sandstone, it will not be easy to wipe it off, because some of it will
have sunk into the stone.

In many places the gas forces its way out, and is piped to carry to
houses for light and heat. Not far above Niagara Falls there was a
spring of gas which flowed for years. An iron pipe was put down, and
when the gas was lighted, the flame shot up three or four feet. The
gas came with such force that a handkerchief put over the end of the
pipe would not burn, though the flame would blaze away above it. In
the country of the fire worshipers, on the shores of the Caspian Sea,
fires of natural gas have been burning for ages, kindled, perhaps, by
lightning centuries ago. There is a vast supply of oil in this place;
and indeed there is hardly a country that has not more or less of it.

In the United States the colonists soon learned that there was
petroleum in what is now the State of New York; but New York was a
long way from the Atlantic seaboard in those days, and they went on
contentedly burning candles or sperm whale oil, or, a little later, a
rather dangerous liquid which was known as "fluid." The Indians
believed that the oil which appeared in the springs was a good
medicine. They threw their blankets upon the water, and when these had
become saturated with the oil, they wrung them out and sold the oil.
Those were the times when if a medicine only tasted and smelled bad
enough, people never doubted that it would cure all their diseases,
and they gladly bought the oil of the Indians.

When at last it became clear to the members of an enterprising company
that oil for use in lamps