"I can feel an awful pressure on my ear drums!" suddenly exclaimed
Harry.
"No wonder," was Frank's rejoinder; "look at that."
He pointed to the gauge.
The dirigible had now been driven to a height of eighteen thousand five hundred feet, and breathing was really becoming painful.
Desperately Frank struggled to get the sinking planes to act, but the wind pressure on the bag counteracted all his efforts in this direction. So fast was the hurricane now driving the gas-bag ahead that the sub-structure lagged behind, straining at its confining stays and braces.
All at once Harry gave a cry and sank to the floor of the pilot-house.
Malvoise, the next instant, hastened to the deck and cried:
"Air, air!"
Frank felt a warm liquid streaming from his nose and ears. He put up his hand. It came away stained red. Even tough old Ben Stubbs felt the baleful effect of the high altitude.
"I'll be hornswoggled if I can stand this much longer," he gasped out to Frank.
"Can you take the wheel?" replied the young aviator. Ben nodded.