They now knew who the mail thief was.
By this time the Bradys were sunk in the quick-sand to their hips, and were unable to move in any direction.
They kept sinking every moment with horrible rapidity.
"Well, we can't arrest you now for that crime," said Old King Brady, "but I've got a feeling that we shall do so yet."
"Humbug! You are getting dopy. You can't escape from there."
"Are you going to abandon us to our fate?"
"Yes; I wish you a merry voyage over the River Styx!"
And with a mocking bow and a jeering laugh, he strode away.
The Bradys began to shout for help again, and Mason paused, and, darting an angry look at them, he shouted threateningly:
"If you don't shut up we'll shoot you!"