These principles, duly observed, will prevent collisions, but they will often cause trains to lose a great deal of time. The train-despatcher, therefore, has authority to handle extra and delayed trains by direct telegraphic order. Every possible precaution is taken to insure that such orders are received and correctly understood. As there are great advantages following uniformity of usages and rules among connecting roads, after years of conference, in conventions and by committees, approved forms of all running rules and signals have recently been adopted and are now in very general use over the United States. Yet, in spite of all possible precautions, accidents will sometimes happen. Richard Grant White gave a name to a mental habit which, in train-despatchers, has caused many fatal accidents. It is "heterophemy," or thinking one thing while saying, hearing, or reading another. A case within my knowledge, which cost a dozen lives, was as follows: Two opposing trains were out of time, and the train-despatcher wished to have them meet and pass at a certain station we will call "I," as Nos. 1 and 2 are represented as doing on the diagram (see diagram of schedule board, p. 161). So he telegraphed the following message, to be delivered to No. 1 at "H" and to No. 2 at "J": "Nos. 1 and 2 will meet at 'I.'" This message was correctly received at "J" and delivered to No. 2. But at "H" the operator had just sold a passenger a ticket to "K," and, getting this name in his head, he wrote out the message: "Nos. 1 and 2 will meet at 'K.'" But the mistake was not yet past correction. The operator had to repeat the message back to the despatcher, that the latter might be sure it was correctly understood. He repeated it as he had written it--"K." But the despatcher was also "heterophemous." He _saw_ "K," but he _thought_ "I," and replied to the operator that the message was O. K. [Illustration: Entrance Gates at a Large Station.] So it was delivered to No. 1, and that train left "H" at full speed, expecting to run thirty-five miles to "K" before meeting No. 2. There was no telegraph office at "I," and there were no passengers to get off or on, and it passed there without stopping, and three miles below ran into No. 2 on a curve. By one of those strange impulses which seem to come from some unconscious cerebration, the train-despatcher meanwhile had a feeling that something was wrong, and looked again at the message received from "H" and discovered his mistake. But the trains were then out of reach. He still hoped that No. 2 might arrive at "I" first, or that they might meet upon a straight portion of road, and as the time passed he waited at the instrument in a state of suspense which may be imagined. When the news came he left the office, and never returned.