We were compelled to grope our way forward with hands pressed against the walls.

I had not advanced more than thirty feet, my every nerve tingling, when I saw the ruddy reflection of a fire, hitherto completely concealed by a sharp turn in the tunnel.

Rounding this abrupt point we found ourselves in a large room capable of containing upwards of three hundred persons.

This chamber was partly natural in formation, but, as I discovered later, had been considerably enlarged by artificial means.

So high was it that, in the dim light, I could scarcely distinguish its vaulted roof, while its length was hidden in the darkness.