The constable, for the moment, had utterly lost his nerve. He stood there in the great flaring roar of the gas mains with a dazed expression that was pitiful.

"Can you tell us anything about it?" Lord Barcombe asked.

"I was in Piccadilly," was the reply. "Everything was perfectly quiet, and so far as I could see not a soul was in sight. Then I heard a funny rushing sound, just like the tear of an express train through a big, empty station. Yes, it was for all the world like a ghostly express train that you could hear and not see. It came nearer and nearer; the whole earth trembled just as if the train had gone mad in Piccadilly. It rushed past me down St. James\'s Street, and after that there was an awful smash and a bang, and I was lying on my back in the middle of the road. All the lights that remained went out, and for a minute or two I was in that railway collision. Then, when I got my senses back, I blundered down here because of that big flaring light there; and I can\'t tell you, gentlemen, any more, except that the tube has blown up."

Of that fact there was no question. There were piles of débris thrown high in one part, and a long deep depression in another like a ruined dyke. A little further on the steel core of the tube lay bare with rugged holes ripped in it.

"Some ghastly electric catastrophe," Sir George Egerton murmured.

It was getting light by this time, and it was possible to form some idea of the magnitude of the disaster. Some of the clubs in St. James\'s Street still appeared to be intact, but others had suffered terribly. The heaps of tumbled masonry were powdered and glittering with broken glass and a few walls hung perilously over the pavement. And still the gas main roared on until the flame grew from purple to violet, and to straw colour before the coming dawn. If this same thing had happened all along the network of tubes, London would be more or less a hideous ruin.
The explosion had had a straight run here, for the road had been raised like some gigantic zigzag molehill.

For the better part of Piccadilly things were brighter. Evidently the explosion had had a straight run here, for the road had been raised like some mighty zigzag molehill for many yards. The wood pavement scattered all over the place suggested a gigantic box of child\'s bricks strewn over a nursery floor. The tube had been forced up, its outer envelope of concrete broken so that the now twisted steel core might have been a black snake crawling down Piccadilly. Doubtless the expanding air had met with some obstacle in the tube under St. James\'s Street, hence the terrible force of the explosion there.

There was quite a large crowd in Oxford Street. The whole roadway was wet; the gutters ran with the water from the broken pipes. The air was full of the odour of gas. All the clocks in the streets seemed to have gone mad. Lord Barcombe glanced at his own watch, to find that it was racing furiously.

"By Jove!" he whispered excit............