None comes.

A snow-wrapt grave at midnight is not more silent.

In vain does he try to catch even the faintest sound of breathing, though he listens intently enough to hear the beating of their hearts; but he hears only his own.
"Call that roll again!" he mutters in a voice far less assured than before; "Barbican! MacNicholl!" The same fearful unearthly stillness.
"The thing is getting decidedly monotonous!" he exclaimed, still speaking French.

Then rapidly recovering his consciousness as the full horror of the situation began to break on his mind, he went on muttering audibly: "Have they really hopped the twig?
Bah! Fudge! what has not been able to knock the life out of one little Frenchman can't have killed two Americans! They're all right! But first and foremost, let us enlighten the situation!" So saying, he contrived without much difficulty to get on his feet.
Balancing himself then for a moment, he began groping about for the gas.
But he stopped suddenly.
"Hold on a minute!" he cried; "before lighting this match, let us see if the gas has been escaping.

Setting fire to a mixture of air and hydrogen would make a pretty how-do-you-do! Such an explosion would infallibly burst the Projectile, which so far seems all right, though I'm blest if I can tell whether we're moving or not." He began sniffing and smelling to discover if possible the odor of escaped gas.