The String of Pearls (1850), p. 570

"I shall be free!" he muttered. "I shall be free! Did they think to hold me with these chains? Ha! ha! No. It may be, that there is a dark spirit of evil that aids men, such as I am; and if it be so, I will consent to be wholly his, if—"
Todd started, for the same noise that had before come upon his ears, now attracted him. It was plainer though than before ; and at the moment he thought that it must be in his cell. A cry of terror rose to his lips, but he smothered it in the utterance, and bent again all his faculties to listen.
The sound did not now pass away like an echo as it had done before, but it went on steadily, and he could trace it as localising itself against one of the walls of the cell.
It was a profound mystery. He could not make out what it meant. It was a strange dull scraping noise. At times he thought it was some animal in the cell—a rat, probably; but then the sound was too continuous, and although he stamped once, and said 'Hush!' several times, it steadily continued.
The darkness in the cell was now so intense, that it was in vain to attempt to pierce it. Any straining of the eyes only peopled the palpable black atmosphere with all sorts of strange shapes, conjured up by the imagination; so Todd was glad to close his eyes after a few moments' experience of that character.
"I will know what this it," he said, "I must know what this is, and I will know!"
He held out his arms, and he slowly advanced towards the side of the cell from whence the sound came.
"Speak," he said, "if you are mortal, speak. If immortal, I fear you not. I am now past all such terrors. You can but kill me."
His hands touched the cold stone wall ; and then he felt it from the floor upwards, but nothing but the chill surface of the stones was perceptible; and
yet the scraping noise continued, and at last he felt convinced that it came from the other side of the wall.
Now he did not know what to think, for he had no means of knowing what was upon the other side of that wall. It might be a corridor of the prison. It might be a room belonging to one of the officials, who was about some work that, if explained, would not appear singular at all.
He placed his ear to the exact spot from whence the noise came, and he listened attentively.
As he so listened, Todd began to have other notions about that noise, and for more than once the square block of stone, against which his ear reposed, shook
in its place.
"It must be a cell like this," he said, "that is on the other side of the wall, and that, no doubt, is some prisoner at work, trying to effect his escape. If so, it is fortunate. He must be a bold man, and we can help each other."
Still Todd hesitated what he should do, notwithstanding the hypothesis regarding the noise he heard appeared so very probable. He was resolved to spend a little more time in listening, for he felt that once to commit himself would possibly be to spoil his own chances of escape. He kept his ear to the stone of the wall, then which shook more and more each passing moment.
Suddenly he heard a voice, In a drawling accent, it sang a few lines of a popular thieves' song—

"The beak looked big, and shook his head,
Heigho, the beak!
He wished such family cares were dead,
That honest folks might get their bread,

Heigho, the beak!
The family cove, he grinned a grin,
Heigho, the cove!
Says he, to prig I think no sin;
or sure a Romany must have tin:

Heigho, the cove!