There was no need to explain to the others what the bad news from the engine-room was. They had guessed from his reply.
And still the dirigible rose.
She was now at an altitude of fifteen thousand feet, and even as Frank gazed at the indicator she soared higher.
It grew bitterly cold.
"Something will have to be done," he shouted to Malvoise, "if we keep on going higher the air will soon be so rarefied that we shall be unable to breathe."
"Set your dropping planes," shouted Malvoise, above the turmoil.
"I have tried to," yelled back Frank, "but she won't drop unless the engine forces her ahead faster. The wind is stronger than we are."
"Let out the gas," suggested Harry.
Frank shook his head.
"I don't want to do that except in case of actual necessity," he said.
"We may need all we have before long."