“They will do,” said Michael; “put a truck in front of the engine and arrange the flares so that they light up the line.” He spent the night in an open truck, slowly passing down the line searching for some clue which would afford a solution to the mystery. Particularly thorough was his search of the three tunnels, but they yielded nothing, and he reached Seahampton as the dawn was breaking without having made any discovery which would help him. He went back to town by the break-down train, sleeping in the guard’s caboose, and reached Quexley in time to receive from the retiring signalman the story of his eccentric gates. Michael was interested and with the man for a guide he followed the course of the controlling wire which passed through a length of iron piping from the signal box to the gate. “The electrician tells me that the wire has been cut somewhere,” said the man. “He has tried his instrument on it.” “The wire cannot be cut if it is inside the iron casing,” said Michael. “It is either cut or fused,” said the man. The detective walked very slowly, pausing now and again to examine the black painted pipe. Presently he stopped. He had detected something and stooped to examine the pipe more closely. It was clear that it had been freshly painted. He passed his hand round it slowly and suddenly he felt an unexpected softness. “This isn’t iron,” he said. He took out his pocket-knife and scraped. A little hole had been burnt into the steel by a portable blow-pipe and the wires inside had been fused together by the heat. “That explains it,” said Michael. “What effect would this have on the gates?” he asked. “Well, you couldn’t open them from the box,” said the man. “Could you open them by hand?” “Yes, sir. We’ve got a chap on duty now who does nothing but open and shut them,” said the man. “While the current is on, they are locked. They work like ordinary gates, except you have to be very careful when you lock them.” Michael waited until a train had passed and then experimented. The gates opened and closed easily enough. “What do you mean when you tell me that you have to be careful with the catch?” “Well, ordinarily, when you use it without the current,” said the man, “the catch falls and cannot be lifted except by electric control.” Michael made an inspection of the “catch.” It was a steel block working on a pivot and obviously operated magnetically. “It doesn’t go up or down, now,” said Michael after testing it. “It looks to me,” said the man, “as though it has been forced up.” There was no doubt that what he said was true for the detective saw the unmistakable mark of a jemmy on the wooden casing about the lock.