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 flat-boats 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 pro-cured 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 thou-sand 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.