Did we make blunders? We simply reveled in ignorance; we learned by making mistakes and by occasionally discovering some of them. We did not know for what to look, but we looked at everything, for everything was a revelation. Some of the worst errors in correlation were due to this. On my third day, while day-dreaming over what seemed to be a remarkable phenomenon, I lost hold of the section, and in crossing the divide committed an error which affected my work throughout that summer and the next. There was no opportunity for revision; the western method of reconnaissance prevailed and a line once covered was completed. The young men, who did the work for their expenses, gained a vast amount of knowledge but not much modesty; they had been found capable of doing a new type of work without assistance. The rod of correction was applied somewhat more than ten years later by Professor Edward Orton, Sr., but the application was made so gently, so courteously, that all of us were united in gratitude to the keen man who had harmonized conflicting observations and had corrected errors, but had administered no rebuke to the incompetent youths who had made them. Economically, the errors were unimportant as they were chiefly in correlation; the resources of state were described well and the observations were recorded honestly. A group of geologists were trained, who, under Orton during the third survey, knew for what to look, how to look for it and, better still, how to present their results.
The second survey of Pennsylvania was ordered by the Legislature of that state in 1874, forty years ago, and J. P. Lesley was appointed as director. Though a survivor of the first survey, discontinued more than 30 years before, he was still in the prime of his powers and, along certain lines, he was perhaps the ablest geologist in the country. But he had entered from the topographical side and all his work had been concerned with economic applications of geology. The survey had been ordered on an extensive scale that the mineral resources of the state might be determined in practical detail, so that it was necessary to publish prompt and somewhat voluminous reports in order to suppress recalcitrant legislators. In 1875 I was appointed geologist in charge of the southwestern district and entered upon the work with I. C. White as aid. It may be remarked in passing that, in state work, the geologist must contend with one serious cause of error which is unknown to the western explorer. Sleepless nights were rare during the western work, but in the civilized region, where one must live off the country, there is often the terror that walketh in darkness, which benumbs the geologist’s intellect and blinds his eyes during the day.
Thirty-five years prior to our advent, Henderson had completed his work for the first survey and had reached the conclusion that, owing to lack of exposure, the upper part of the section would never be worked