The line between these tunnels was so crooked and obscured that the managers had adopted extraordinary precautions against accident. At each end of the Croydon Tunnel a signal-man was stationed, with a telegraphic apparatus, a clock and a telegraph bell in his station. The rule was absolute that when any train entered the tunnel the signal-man at the point of entry was to telegraph "train in," and no other train could follow until the return signal of "train out" came from the other side. In face of such a regulation it was difficult to see how any collision in the tunnel was possible. When the Portsmouth excursion train arrived, it at once entered the tunnel and the fact was properly signaled to the opposite outlet. Before the return signal that this train was out was received, the regular excursion train came in sight. It should have been stopped by a self-acting signal which was placed about a quarter of a mile from the mouth of the tunnel, and which each passing locomotive set at "danger," where it remained until shifted to "safety," by the signal-man, on receipt of the message, "train out." Through some unexplained cause, the Portsmouth excursion train had failed to act on this signal, which consequently still indicated safety when the Brighton excursion train came up. Accordingly the engine-driver at once passed it, and went on to the tunnel. As he did so, the signal-man, perceiving some mistake and knowing that he had not yet got his return signal that the preceding train was out, tried to stop him by waving his red flag. It was too late, however, and the train passed in. A moment later the parliamentary train also came in sight, and stopped at the signal of danger. Now ensued a most singular misapprehension between the signal-men, resulting in a terrible disaster. The second train had run into the tunnel and was supposed by the signal-man to be on its way to the other end of it, when he received the return message that the first train was out. To this he instantly responded by again telegraphing "train in," referring now to the second train. This dispatch the signal-man at the opposite end conceived to be a repetition of the message referring to the first train, and he accordingly again replied that the train was out. This reply, however, the other operator mistook as referring to the second train, and accordingly he signaled "safety," and the third train at once got under way and passed into the tunnel. Unfortunately the engineer of the second train had seen the red flag waved by the signal-man, and, in obedience to it, stopped his locomotive as soon as possible in the tunnel and began to back out of it. In doing so, he drove his train into the locomotive of the third train advancing into it. The tunnel was twenty-four feet in height. The engine of the parliamentary train struck the rear carriage of the excursion train and mounted upon its fragments, and then on those of the carriage in front of it,