And taken with the context, this is full of meaning.

Now Jonah's Captain, shipmates, was one whose discernment detects crime in any, but whose cupidity exposes it only in the penniless. In this world, shipmates, sin that pays its way can travel freely and without a passport; whereas Virtue, if a pauper, is stopped at all frontiers. So Jonah's Captain prepares to test the length of Jonah's purse, ere he judge him openly. He charges him thrice the usual sum; and it's assented to. Then the Captain knows that Jonah is a fugitive; but at the same time resolves to help a flight that paves its rear with gold. Yet when Jonah fairly takes out his purse, prudent suspicions still molest the Captain. He rings every coin to find a counterfeit. Not a forger, any way, he mutters; and Jonah is put down for his passage. 'Point out my state-room, Sir,' says Jonah now, 'I'm travel-weary; I need sleep. Thou look'st like it,' says the Captain, 'there's thy room.' Jonah enters, and would lock the door, but the lock contains no key. Hearing him foolishly fumbling there, the Captain laughs lowly to himself, and mutters something about the doors of convicts' cells being never allowed to be locked within. All dressed and dusty as he is, Jonah throws himself into his berth, and finds the little state-room ceiling almost resting on his forehead. The air is close, and Jonah gasps. Then, in that contracted hole, sunk, too, beneath the ship's water-line, Jonah feels the heralding presentiment of that stifling hour, when the whale shall hold him in the smallest of his bowels' wards.