out. During that interval there had been no change in conditions except that the region had been stripped of forest and numerous rude country roads had been made. There was no railroad, except at the extreme north; there were no extensive mining operations except on the Pittsburgh coal bed on the Monongahela River, and there were no records of oil borings except in the southeast corner where they were not needed. To add to the natural drawbacks, we were equipped with aneroids which were fearfully and wonderfully made. Lesley, unable to induce Becker to make a supply of high grade barometers, had procured a number of models to be tested. Those assigned to us were shaped like a hat box and were provided with vernier and other attachments, all of which had to be cared for at each reading, as otherwise the observation would be wholly worthless. Happily for us, our horses ran away one day; when the race was over and White’s horse had won, we discovered with grateful hearts that the barometers were ruined. Thereafter we used our own barometers, which proved to be fairly good.
As soon as we had passed beyond 100 feet above the Waynesburg coal bed, satisfactory exposures became rare—and nine tenths of Greene County, in which we had begun, was above that horizon. The only recourse was to examine every bit of rock that jutted out on a hillside. Sections were made everywhere, 5 to 100 or more feet long, but the longer ones had tormenting gaps which refused to be filled. Strange anomalies appeared, which cast doubt on tentative correlations; limestone was found where we expected variegated shale; streaks of coal appeared in what seemed to be wrong positions; sandstone was seen where there should have been a coal bed. Our work proved that these are not anomalies and the conditions are commonplaces to-day; but 40 years ago the continuity of deposits was a cardinal doctrine and all limestones were marine. Our conversion was slow but it came, and little by little we were able to piece the fragments together; the section was completed as far as possible and doubt remained respecting only a few horizons, which were not economically important.
It would have been well if several localities could have been re-examined; a number of errors would have been eliminated which now are so evident that any one can note them. Revision is very different from original work, and is a very simple matter. If the original observer has recorded his observations honestly, the reviser needs no especial acumen in order to discover the errors. If White and I had had the advantage, 40 years ago, of the hundreds of oil-well records made in the Greene and Washington district during the last 20 years, our work would have been a holiday jaunt; we should not have been compelled to spend so many dreary days in securing fragmentary sections or so many weary nights in trying to combine them. But there were no well records and there was no opportunity for revision. Too