One day the president of the bank, Mr. Pratt, was surprised, on entering the vault, to find the floor sprinkled with a fine white dust. An investigation was made, and the whole plot was uncovered. The members of the gang, however, got word in time, and all managed to escape except Perry, who was convicted of attempted burglary and sent to the Auburn prison for five years. Undisturbed by the failure, Scott and Dunlap proceeded to scour the country again in search of another bank suited to their operations, and in February, 1874, notified the gang, which now contained some new members, that they had "found something to go to work at" in Quincy, Illinois. The attack on the Quincy bank was made in very much the same way as the attack on the bank at Elmira. The Baltimore woman again rented a house which afforded shelter and concealment to the men; access was obtained to rooms over the vault by false keys, as before; the flooring was taken up and put down every night without exciting suspicion; the masonry was removed, the iron plates of the vault were penetrated, and, finally, one night Scott and Dunlap were able to lower themselves through a jagged hole into the money-room beneath. It now remained to force open the safes inside the vault; and to accomplish this the robbers used, for the first time in the history of safe-wrecking in America, what is known as the air-pump method, which had been devised by Evans, and carefully explained by him to Scott and Dunlap. Evans's employers were at this time introducing a padding designed to make safes more secure; and Evans had hit upon the idea of introducing powder into the seams of a safe-door by an air-pump, in the presence of a possible customer, in order to impress him with his need of the new padding. Evans himself was not present at the breaking open of the Quincy bank, and he had nothing to do with the robbery beyond furnishing instruction and the air-pump. Scott and Dunlap did the work.