The gang's most desperate adventure befell in connection with the attempt on the First National Bank of Pittston, Pennsylvania. This was made late in the fall of 1875. The bank occupied a one-story building covered with a tin roof, and the robbers decided to make the attack from the roof. But there was a serious difficulty in the fact that in case of rain coming any time after they had begun operations, water might soak through the openings they had made and betray them. Dunlap's ingenuity, however, was equal to this emergency; and each night, after finishing their excavation, they carefully relaid the sheets of tin that had been disturbed, protecting the joints with red putty, which matched the roof in color. So well did they put on this putty, that, although it rained heavily the very day after they began, not a drop leaked through. On the night of November 4 only one layer of bricks separated them from the top of the vault, and it was decided to finish the work and do the robbery that night. Two hours' hard labor with "drag" and "jack-screw" sufficed to effect an opening, and Scott and Dunlap were lowered into the vault. They found three Marvin spherical safes protected by a burglar-alarm. But Dunlap was somewhat of an electrical expert, and was able to so surround the burglar-alarm with heavy boards as to render it of little or no danger. They experienced much difficulty, though, in blowing open the safes. The first one attempted yielded on the second explosion, and they secured five hundred dollars in currency and sixty thousand dollars in bonds. The next one was far more troublesome, not less than ten explosions being required to make way into it. And just as the task was at last accomplished, and they were on the point of seizing a great sum of money, there came a warning call from Conroy, who was doing sentry duty on the roof, and it was necessary to fly. When Dunlap and Scott had been dragged out of the vault by their associates, they were found scarcely able to run. During all the twelve explosions of powder and dynamite they had never left the vault, but, crouching behind the boards that guarded the burglar-alarm, had remained within arm's length of explosions so violent that they tore apart plates of welded steel and shook the whole building. Worse than the shock of these explosions were the noxious gases generated by them, which Scott and Dunlap had to breathe. On coming out, their clothes were wringing wet with perspiration, and they were so weak that their legs tottered under them, and their comrades had to almost carry them for a time. But, nevertheless, they managed to walk thirty miles that night, to Lehigh, where they boarded a train to New York. It was on this occasion that there was left behind in the vault the air-pump which Robert Pinkerton afterward recalled so shrewdly to Evans's disadvantage.