And now the thread went downwards, and led Irene's hand to a hole in the floor of the cavern, whence came a sound of running water which they had been hearing for some time.
'It goes into the ground now, Curdie,' she said, stopping.
He had been listening to another sound, which his practised ear had caught long ago, and which also had been growing louder.

It was the noise the goblin-miners made at their work, and they seemed to be at no great distance now.

Irene heard it the moment she stopped.
'What is that noise ?' she asked.

'Do you know, Curdie ?' 'Yes.

It is the goblins digging and burrowing,' he answered.
'And you don't know what they do it for ?' 'No; I haven't the least idea.