Although the robbery was at once reported to Mr. M. J. O'Brien, the General Superintendent, by telegraph, no action seems to have been taken until the following Wednesday--four days later--when Mr. O'Brien sent me a brief telegram announcing the robbery, and requesting me to come to Union City in person, if possible, and if not, to send my eldest son, William A. Pinkerton. The telegraph was used freely for the next two days, and while my son was gathering clues and making his preparations, we learned most of the facts by letter. William arrived in Union City on Saturday, just one week after the robbery had been committed, and he instantly began to gather information from every available source. Except the statements of the negro porter and Thompson, the guard, as condensed in the account heretofore given, little information could be obtained, as so few persons were about the train when it began to move off. While two or three had seen the men who had entered the car, no one had seen who had run the locomotive, and there was, therefore, no certainty as to the number of persons engaged in the job. One passenger had seen two men walking toward the engine in a suspicious manner, and, as his description of these two was entirely different from that given of the men who had entered the car, it was fair to presume that they had been a part of the gang. Still, no one had seen them get on the engine, and it was not certain that they had had anything to do with the affair. At the end of three days, however, William had collected sufficient information to satisfy himself that either four or five men had been at work together; and, by collating the various descriptions he received, he obtained a pretty fair idea of the party. The first thing which struck him was the similarity of this robbery to the one which had occurred exactly three months before at Moscow, Kentucky. The appearance of the men and their actions had been precisely like those of the Moscow party, and it was evident that they had been emboldened to a second venture by the ease with which they had carried through their former scheme. One thing was imperative: the capture of the whole gang would be necessary to insure the safety of the express company's property in the future. Indeed, it was a mere piece of good fortune that the loss in this instance was not irreparable, for the amount of money carried on the southern-bound train was eighty thousand dollars, and the robbers would have obtained this large amount if the southern-bound train had chanced to arrive first. The robbery was clearly one which no common tramp or sneak-thief would have dared to attempt, and William saw immediately the difficulties of his work. Before proceeding with the incidents of the operation, I must give some idea of the country and the people living there, since no-one would otherwise comprehend one-half of the obstacles and dangers which were involved in a search for the criminals in that vicinity.