defined.  At the principal field, that of Murraysville (from which most of the gas is obtained to-day), I found, upon my visit to that interesting region last autumn, that nine wells had been sunk, and were yielding gas in large quantities.  One of these was estimated as yielding 30,000,000 cubic feet in 24 hours.  This district lies to the northeast of Pittsburg, running southward from it toward the Pennsylvania Railroad.  Gas has been found upon a belt averaging about half a mile in width for a distance of between four and five miles.  Beyond that again we reach a point where salt water flows into the wells and drowns the gas.  Several wells have been bored upon this belt near the Pennsylvania Railroad, and have been found useless from this cause.  Geologists tell us that in this region a depression of 600 feet occurs in the strata, but how far the fault extends has not yet been ascertained.  Wells will no doubt soon be sunk southward of the Pennsylvania Railroad upon this half-mile belt.  Swinging round toward the southwest, and about twenty miles from the city, we reach the gas fields of Washington county.  The wells so far struck do not appear to be as strong as those of the Murraysville district, but it is possible that wells equally productive may be found there hereafter.  There are now four wells yielding gas in the district, and others are being drilled.  Passing still further to the west, we reach another gas territory, from which manufacturing works in Beaver Falls and Rochester, some twenty-eight miles west of Pittsburg, receive their supply.  Proceeding with the circle we are drawing in imagination around Pittsburg, we pass from the west to the southwest without finding gas in any considerable quantity, until we reach the Butler gas field, equidistant from Pittsburg on the northwest, with Washington county wells on the southwest.  Proceeding now from the Butler field to the Allegheny River, we reach the Tarentum district, still about twenty miles from Pittsburg, which is supplying a considerable portion of the gas used.  Drawing thus a circle around Pittsburg, with a radius of fifteen to twenty miles, we find four distinct gas-producing districts.  In the city of Pittsburg itself several wells have been bored; but the fault before mentioned seems to extend toward the center of the circle, as salt water has rushed in and rendered these wells wholly unproductive, though gas was found in all of them.

I spent a few days very pleasantly last autumn driving with some friends to the two principal fields, the Murraysville and the Washington county.  In the former district the gas rushes with such velocity through a 6-inch pipe, extending perhaps 20 feet above the surface, that it does not ignite within 6 feet of the mouth of the pipe.  Looking up into the clear blue sky, you see before you a dancing golden fiend, without visible connection with the earth, swayed by the wind into fantastic shapes, and whirling in every direction.  As the gas from the well strikes