The four counties adjoining Pittsburg turn out over thirty millions of
tons of bituminous coal in a year. To carry this coal away, besides
railways, the city has about a million and a half of tonnage of river
craft of various kinds, a greater tonnage than all the Mississippi
River ports put together. Its coal boats go everywhere throughout the
Western water ways, and two thousand miles down the Ohio and
Mississippi to New Orleans. Its stumpy but powerful little tugs, with
their stern-wheels, will safely convey fleets of shallow flatboats,
sometimes over twenty thousand tons of coal being carried in a single
tow. These flatboats are collected in the rivers about Pittsburg,
waiting for the proper stage of water on the Ohio; and to regulate the
depth at the city the curious movable dam was constructed at Davis's
Island, four miles below Pittsburg, at a cost of $1,000,000, the dam
opening when necessary to let freshets through, and having a lock five
hundred feet long and one hundred and ten feet wide to pass the boats.
The Monongahela River above Pittsburg has for miles a series of coal
mines in the high bordering banks, the river being lined with coal
"tipples," which load the flatboats; and it is also provided with a
series of dams, which aid navigation and divide the channel into a
succession of "pools." The very crooked Youghiogheny flows in at
McKeesport, fifteen miles above Pittsburg, another river of coal
mines, whose name was given as a signification of its crookedness by
the matter-of-fact Indians, the word signifying "the stream flowing a
contrary, roundabout course." This river comes northward out of the
chief coke district of America, in the flanks of the long Chestnut
Ridge, the Connellsville coke region sometimes turning out ten
millions of tons annually from its ovens. Railways run in there on
both river banks to Connellsville, a town of six thousand people, in
the midst of the coke ovens, and about fifty-six miles south of
Pittsburg.
Pittsburg is decreasing its use of natural gas for manufacturing, as
the diminishing supply and greater distance it has to be brought are
making it too costly for the iron and glass works, which are returning
again to coal and coke, but the city is still said to use forty-five
thousand millions of cubic feet in a year, mostly for domestic
purposes. Pittsburg stands in a great but partly exhausted natural-gas
district. The gas is stored under pressure beneath strata of rock,
being set free when these are pierced. This is a gaseous member of the
paraffin series, of which petroleum is a liquid member, and is mainly
marsh-gas, the "fire-damp" of the miner. It originates in the
decomposition of animal and vegetable life, and usually has but little
odor, whilst its illuminating power is low, but in fuel value eight
cubic feet equal one pound of coal. It was first used at Fredonia, New
York, in 1821, for lighting purposes, being procured from a well. The
natural-gas region is the part of Pennsylvania west of the
Alleghenies, extending into New York, Ohio and West Virginia; and gas
is also found in Indiana, Illinois, Kentucky and Kansas. It is held
under enormous pressure within the pockets beneath the rocks, and when
first reached in drilling, the tension has been known to equal a
thousand pounds per square inch. It is not uncommon, when a well is
drilled, to have all the tools and casing-pipe blown out, while an
enormous thickness of masonry has to be constructed to hold down the
cap that covers the well. Its use began in Pittsburg in 1886, the
chief field of supply then being Murrysville, about twenty miles east
of the city, while there are also other fields southwest and east of
Pittsburg. The pipes underlie all the streets, and a main route of
supply is along the bed of the Allegheny River. There are said to be
about sixteen hundred miles of pipes laid down to lead the gas to
Pittsburg from the different fields.