store-room below the floor of the Golden Eagle and pointed to a
dozen cylindrical steel receptacles. "They contain more than enough
pure hydrogen gas at a high pressure," he explained, "to inflate the
bag."

In his enthusiasm Harry waved his helmet and Ben did the same.

"An aerial express, hurray!"

The inflation hose was soon connected to the first of the cylinders
and with a hiss the gas rushed into the bag when a turn of the
wrench set free the precious stuff. Slowly the big yellow envelope
swelled and assumed shape until by the time the last cylinder was
empty it was tugging and straining to rise. But the boys had
weighted it down with rocks and pegged its net ropes to the ground.

The ivory was loaded into a sort of rope basket, like those used to
hoist cargo aboard a ship, and in a short time, so quickly did they
work, they were ready for the air, so far as what Harry called "the
airbarge" was concerned.

"We shall have to strip the Eagle," decided Frank, when the
inflation job was finished.

"Of everything that we can spare," added Harry, setting to work at
once to rip the transoms and detach the bolts that held the heavy
wireless apparatus in place. As he did so, Frank was moved by a
sudden thought.

"Hold on a second, Harry," he shouted, "I'll call up the river camp