as yet, and the gas bag had not
been inflated as Tom wanted to try the plane feature first. But the
vapor machine was all ready to start generating the gas whenever it
was needed. Nor was the Black Hawk painted and decorated as she
would be when ready to be sent to Africa. On the whole, she looked
rather crude as she rested there on the bicycle wheels, awaiting the
starting of the big propellers. As the stores and supplies were not
yet in, Tom took aboard, in addition to Mr. Damon, Ned, his father,
Mr. Jackson and Mr. Durban, some bags of sand to represent the extra
weight that would have to be carried.

"If she'll rise with this load she'll do," announced the young
inventor, as he went carefully over the craft, looking to see that
everything was in shape.

"If she does rise it will be a new experience for me," spoke the old
elephant hunter. "I've never been in an airship before. It doesn't
seem possible that we can get up in the air with this machine."

"Maybe we won't," spoke Tom, who was always a little diffident about
a new piece of machinery.

"Well, if it doesn't do it the first time, it will the second, or
the fifty-second," declared Ned Newton. "Tom Swift doesn't give up
until he succeeds."

"Stop it! You'll make me blush!" cried the Black Hawk's owner as he
tried the different gages and levers to see that they were all
right.

After what seemed like a long time he gave the word for those who
were to make the trial trip to take their places. They did so, and
then, with Mr. Jackson, Tom went to the engine room. There was a
little delay, due to the fact that some adjustment was necessary on
the main motor. But at last it was fixed.

"Are you all ready?" called Tom.

"All ready," answered Mr. Damon. The old elephant hunter sat in a
chair, nervously gripping the arms, and with a grim look on his
tanned face. Mr. Swift was cool, as Ned, for they had made many
trips in the air. Outside were Eradicate Sampson and Mrs. Baggert.

"Here we go!" suddenly cried Tom, and he yanked over the lever that
started the main motor and propellers. The Black Hawk trembled
throughout her entire length. She shivered and shook. Faster and
faster whirled the great wooden screws. The motor hummed and
throbbed.

Slowly the Black Hawk moved across the ground. Then she gathered
speed. Now she was fairly rushing over the level space. Tom Swift
tilted the elevation rudder, and with a suddenness that was
startling, at least to the