By means of a spile-driver, an iron pipe, sharp at the lower edge and about six inches in diameter, is driven down until it rests upon the solid rock, usually at a depth of about fifty feet. The earth is then removed from the inside of this pipe by means of a sand-pump, and the "tools" attached to a cable are placed within it.
These tools, consisting of a centre-bit and a rammer, are each thirty or thirty-five feet in length, and weigh about eight hundred pounds. At short intervals these are replaced by the sand-pump, which removes the drillings.
The first three strata of rock are usually slate, sandstone, and soapstone. Beneath these, at a depth of two hundred feet, lies the second sandstone, and from this all the first yield of oil was taken; but, though good in quality, this supply was speedily exhausted, and the modern wells are carried directly through this second sandstone, through the slate and soapstone beneath, to the third sandstone, in whose crevices lies the largest yield yet discovered. The proprietors of old wells are now reaming them out and sinking their shafts to the required depth, which is about four hundred and fifty feet.
The oil announces itself in various ways: sometimes by the escape of gas; sometimes by the appearance of oil upon the cable attached to the tools; sometimes by the dropping of the tools, showing that a crevice has been reached; and in occasional happy instances by a rush of oil spouting to the top of the derrick, and tossing out the heavy tools like feathers.
Such a well as this, known as a flowing well, is the best "find" possible, as the fortunate borer has nothing more to do than to put down a tubing of cast-iron artesian pipe, lead the oil from its mouth into a tank, and then, sitting under his own vine and fig-tree, leave his fortune to accumulate by daily additions of thousands of dollars. A flowing well, struck while Miselle was upon the Creek, yielded fifteen hundred barrels per day, the oil selling at the well for ten dollars and a half the barrel.
But should the oil decline to flow, or, having flowed, cease to do so, a force-pump is introduced, and, driven by the same engine that bored the well, brings up the oil at a rate varying from three to three hundred barrels per day. The Phillips Well, on Tarr Farm, originally a flowing well, producing two thousand barrels per day, now pumps about three hundred and thirty, and is considered a first-class well.
Before reaching oil, the borer not unfrequently comes upon veins of water, either salt or fresh; and this water is excluded from the shaft by a leathern case applied about the pipe and filled with flax-seed. The seed, swollen by the moisture, completely fills the space remaining between the tube and the walls of the shaft, so that no water reaches the oil. But whenever the tubing with its seed-bags is withdrawn, the water rushing down "drowns" not only its own well, but all such as have subterraneous communication with it. In this manner one of the most important wells upon the Creek avenged itself some time ago upon a too successful rival by drawing its tubing and letting down the water upon both wells. The rival retaliated by drawing its own tubing, with a like result, and the proprietors of each lost months of time and hundreds of thousands of dollars before the quarrel could be adjusted.
From the mouth of the shaft, elevated some fifteen feet above the surface of the ground, the oil either flows or is pumped into an immense vat or tank, and from this is led to another and another, until a large well will have a series of tanks connected like the joints of a rattlesnake's tail. Into the last one is put a faucet, and the oil drawn into barrels is either carried to the local refinery, or in its crude condition is boated to the railway, or to Oil City, and thence down the Alleghany.
One of the principal perils attending oil-seeking is that of fire. Petroleum, in its crude state, is so highly impregnated with gas and with naphtha, or benzine as to be very inflammable,—a fact proved, indeed, many years ago, when, as history informs us,
"General Clarke kindled the vapor,
Stayed about an hour, and left it a-burning,"