swiftly knot a strong trail-rope to a heavy iron grapnel, leaving
the other end firmly attached to a stanchion built for that
express purpose.

"Hold fast, if you value life at all, dear boys!" he warned, then
added: "Heaven be kind to you, even if my life pays the forfeit!
Now!"

Without further delay, he cast the heavy grapnel into that mass
of boiling vapour, then fell flat, as an awful jerk was given the
aerostat.



CHAPTER V.
THE PROFESSOR'S UNKNOWN LAND.

There was neither time nor opportunity for taking notes, for that
long rope straightened out in the fraction of a second, throwing
all prostrate as the flying-machine was jerked upward with awful
force.

All around them raged and roared the mighty winds, while missiles
of almost every description pelted and pounded both machine and
inmates during those few seconds of extraordinary peril.

Fortunately neither the professor nor his nephews could fairly
realise just what was taking place, else their brains would
hardly have stood the test; and fortunately, too, that ordeal was
not protracted.