"Eighteen hours," she cried, horror-struck. "Do you mean to say
we may have to stop here, all alone, for eighteen hours together?
Oh, how very dreadful! How long! How frightening! And if they don't
dig us out before eighteen hours are over, do you mean to say we
shall die of choking?"

Cyril gazed down at her with a very regretful and sympathetic face.

"I didn't mean to frighten you," he said; "at least, not more than
you're frightened already; but, of course, there's only a certain
amount of oxygen in the space that's left us; and as we're using
it up at every breath, it'll naturally hold out for a limited time
only. It can't be much more than eighteen hours. Still, I don't
doubt they'll begin digging us out at once; and if they dig through
fast, they may yet be in time, even so, to save us."

Elma bent forward with her face in her hands again, and, rocking
herself to and fro in an agony of despair, gave herself vip to a
paroxysm of utter misery. This was too, too terrible. To think of
eighteen hours in that gloom and suspense; and then to die at last,
gasping hard for breath, in the poisonous air of that pestilential
tunnel.

For nearly an hour she sat there, broken down and speechless; while
Cyril Waring, taking a seat in silence by her side, tried at first
with mute sympathy to comfort and console her. Then he turned to
examine the roof, and the block at either end, to see if perchance
any hope remained of opening by main force an exit anywhere. He
even began by removing a little of the sand at the side of the line
with a piece of shattered board from the broken carriage in front;