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.

THE BALLOON HOAX

diminishing its ascending power. For example, there
may be a deposition of dew upon the silk, to the
extent, even, of several hundred pounds; ballast has
then to be thrown out, or the machine may descend.
This ballast being discarded, and a clear sunshine
evaporating the dew and at the same time expanding
the gas in the silk, the whole will again rapidly ascend.
To check this ascent, the only resource is (or rather
was, until Mr. Green's invention of the guide-rope)
the permission of the escape of gas from the valve;
but, in the loss of gas, is a proportionate general loss
of ascending power; so that, in a comparatively brief
period, the best constructed balloon must necessarily
exhaust all its resources, and come to the earth. This
was the great obstacle to voyages of length.
The guide-rope remedies the difficulty in the simplest
manner conceivable. It is merely a very long rope
which is suffered to trail from the car, and the effect
of which is to prevent the balloon from changing its
level in any material degree. If, for example, there
should be a deposition of moisture upon the silk, and
the machine begins to descend in consequence, there
will be no necessity for discharging ballast to remedy
the increase of weight, for it is remedied, or counteracted, in an exactly just proportion, by the deposit on
the ground of just so much of the end of the rope as
is necessary. If, on the other hand, any circumstances should cause undue levity, and consequent
ascent, this levity is immediately counteracted by the
additional weight of rope upraised from the earth.
Thus, the balloon can neither ascend nor descend,
except within very narrow limits, and its resources,
either in gas or ballast, remain comparatively unimpaired. When passing over an expanse of water, it
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