There was, it seemed, a sudden boom, followed by a long, continuous roar.

Diggory turned his head, to find the far-off patch of light replaced by a spark of fiery red, and the terrible truth flashed across his mind that in the excitement of the moment he could not remember for certain which was the down line.
It was well for the Triple Alliance that at least one of their number was blessed with the faculty of quick decision and prompt action, or the history of their friendship might have had a tragic ending.
Diggory wheeled round, and catching hold of Mugford, cried in a voice loud enough to be heard above the ever-increasing din, "Quick! get into the six-foot way, and lie down!" What followed even those who underwent the experience could never clearly describe.

They flung themselves upon the ground: there were the thundering roar of an earthquake, coupled with a deafening clatter, as though the whole place were falling about their ears, and a whirling hurricane of hot air and steam.
In ten seconds, which seemed like ten minutes, the whole thing had come and gone, and Diggory, scrambling to his feet in the dense darkness of the choking atmosphere, inquired in a shaky voice, "Are you all right, you chaps ?" There was a reply in the affirmative, and the three boys proceeded to grope their way along in silence, until the broad archway of the tunnel's mouth appeared through a fog of steam and smoke.
"I say, you fellows," cried Diggory, as they emerged into the fresh air, "I wouldn't go through there again for something." "It was a good thing you gave me that shove," said Mugford; "I felt as though I couldn't move.

And we were standing on the very line it went over." "Yes: I couldn't remember for the moment which was 'up' and which was 'down.' I thought, too, we should be safer lying flat on the ground when it passed; had we stood up in the six-foot way, we might have got giddy and fallen under the wheels." The conversation was suddenly interrupted by a strange voice shouting,-- "Hullo, you young beggars! what are you a-doing there ?" The boys turned to see from whence this inquiry proceeded.

Half-way up the cutting on their left was a little hut, and beside it stood the man who had spoken.