t was twisting it loose. A similar
formation appeared a few minutes after a short distance behind.

And now began the most extraordinary exhibition of all. Imagine two
whirling balloons, a hundred feet in height, and so black that they
stood out from the surrounding gloom, showing like pitch against the
dimly lit sky behind. They began a witches' waltz in the firmament,
sometimes leaning far backward, then dancing forward, as if saluting
each other, then "balancing," then dancing up and down, then so far away
from each other that one would pass out of the field of vision, soon to
reappear, however. At times they seemed as if about to rush into each
other's arms, and then they coquetted away again and resumed the weird
dance in the skies.

You understand that I am trying to describe one of those terrible
visitations of the west known as a cyclone. Little was heard of them a
century ago, and the balloon to which I have compared the form of the
ghostly dancers, was unknown to the lads, who watched the exhibition
with an interest that was not turned into terror, as it would have been
to-day, by the knowledge of the awful power for death and destruction
that lies within that concentration of electricity in its most fateful
form.

It seemed a long time that this strange scene lasted, though it could
not have been many seconds. Suddenly, while the balloon-like forms were
saluting each other, they rushed together. There was no shock
perceivable when they met, but there were vivid flashes from within the
murky folds, as the heat lightning sometimes plays among the clouds at
the close of a warm day.

Having met, the forms engaged in a wrestling bout. Round and round they
spun with the same bewildering swiftness, leaning far to one side, as
though about to fall, and all the time whirling with such speed on the
one spiral leg that it seemed unable to keep pace with the bulkier part
above.

CHAPTER XXXIII.

FRED LINDEN AWAKENS TO AN ALARMING FACT.

The approach of the cyclone was attended by an appalling roar, and a
mass of branches and trees flying through the air, which warned the boys
of their danger.

"Terry, it won't do to stay here," shouted Fred, casting about for some
place of refuge; "where shall we go?"

Quite close to the stream which they had just crossed was an enormous
rock. Its irregular surface, a dozen feet in extent each way, must have
reached far down in the ground, so that nothing could have b