In the flare of the blue arc lights a dozen men were working on the dome of the core. Something had gone wrong with a water-main overhead, the concrete beyond the steel belt had cracked, and the moisture had corroded the steel plates, so that a long strip of the metal skin had been peeled away, and the friable concrete had fallen on the rails. It had brought part of the crown with it, so that a maze of large and small pipes was exposed to view. "They look like the reeds of an organ," a raw engineer's apprentice remarked to the foreman. "What are they?" "Gas mains, water, electric light, telephone, goodness knows what," the foreman replied. "They branch off here, you see." "Fun to cut them," the apprentice grinned. The foreman nodded absently. He had once been a mischievous boy, too. The job before him looked a bigger thing than he had expected. It would have to be patched up till a strong gang could be turned on to the work. The raw apprentice was still gazing at the knot of pipes. What fun it would be to cut that water-main and flood the tunnels! In an hour the scaffolding was done and the _débris_ cleared away. To-morrow night a gang of men would come and make the concrete good and restore the steel rim to the dome. The tube was deserted. It looked like a polished, hollow needle, lighted here and there by points of dazzling light. It was so quiet and deserted that the falling of a big stone reverberated along the tube with a hollow sound. There was a crack, and a section of piping gave way slightly and pressed down upon one of the electric mains. A tangled skein of telephone wires followed. Under the strain the electric cable parted and snapped. There was a long, sliding, blue flame, and instantly the tube was in darkness. A short circuit had been established somewhere. Not that it mattered, for traffic was absolutely suspended now, and would not be resumed again before daylight. Of course, there were the work-men's very early trains, and the Covent Garden market trains, but they did not run over this section of the line. The whole darkness reeked with the whiff of burning indiarubber. The moments passed on drowsily. Along one side of Bond Street the big lamps were out. All the lights on one main switch had gone. But it was past one o'clock now, and the thing mattered little. These accidents occurred sometimes in the best regulated districts, and the defect would be made good in the morning. It was a little awkward, though, for a great State ball was in progress at Buckingham Palace. Supper was over, the magnificent apartments were brilliant with light dresses and gay uniforms. The shimmer and fret of diamonds flashed back to lights dimmer than themselves. There was a slide of feet over the polished floors. Then, as if some unseen force had cut the bottom of creation, light and gaiety ceased to be, and darkness fell like a curtain.