The works of Edgar Allan Poe; newly collected and edited, with a memoir, critical introductions, and notes, by Edmund Clarence Stedman and George Edward Woodberry; the illustrations by Albert Edward Sterner.

ADVENTURE OF ONE HANS PFAALL

brings me back to the rate at which it would be
possible to travel.
It is true that balloons, in the first stage of their
ascensions from the earth, are known to rise with a
velocity comparatively moderate. Now, the power
of elevation lies altogether in the superior gravity of
the atmospheric air compared with the gas in the
balloon; and, at first sight, it does not appear probable
that, as the balloon acquires altitude, and consequently
arrives successively in atmospheric strata of densities
rapidly diminishing - I say, it does not appear at all
reasonable that, in this its progress upward, the
original velocity should be accelerated. On the other
hand, I was not aware that, in any recorded ascension,
a diminution had been proved to be apparent in the
absolute rate of ascent; although such should have
been the case, if on account of nothing else, on
account of the escape of gas through balloons ill
constructed, and varnished with no better material
than the ordinary varnish. It seemed, therefore, that
the effect of such escape was only sufficient to
counterbalance the effect of the acceleration attained
in the diminishing of the balloon's distance from the
gravitating centre. I now considered that, provided
in my passage I found the medium I had imagined,
and provided it should prove to be essentially what
we denominate atmospheric air, it could make comparatively little difference at what extreme state of
rarefaction I should discover it-that is to say, in
regard to my power of ascending - for the gas in the
balloon would not only be itself subject to similar
rarefaction (in proportion to the occurrence of which,
I could suffer an escape of so much as would be
requisite to prevent explosion), but, being what it was,
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