er more nor less, would it
experience, whether it endeavoured to make this way _against_ a
wind blowing at the rate of 100 miles an hour, or _with_ the same
in its favour. The result, so far as regards its distance from the
place of starting, would, I grant, be very different; but at present
we are only considering the conditions of its motion through the
_air_, and these, I repeat, would be the same whatever the rate
or course of the wind; so that all speculations on this score
must resolve themselves into questions of _quantity_, not of
_quality_, in the effect sought to be accomplished: in other
words, all consideration of the rate of the wind must be left out of
the argument, except, in so far as it shall be taken to regulate the
limit which shall be assigned to the rate of the aerial machine, as
sufficient to justify its claims to the title of a successful mode of
navigating the skies.[A]

[Footnote A: The condition of a Balloon propelled by machinery is very
analogous to that of a boat in the water driven by oars or paddles.
Suppose such a boat to be rowing or paddling up a river against the
stream, if a piece of cork be thrown overboard it appears to be
carried away with the current. But this is delusive; it is the boat
_alone_ which really moves away from the cork. For if the boat be
left to its own course, both it and the cork will float down together;
and if the use of the oars or paddles be resumed, the distance
between the boat and the cork will proceed to develope itself exactly
according to the rate of the _boat_, without any regard to that
of the _stream_. If the stream be excessively rapid, the boatsmen
will appear to be exercising very great force to enable them to stem
the torrent and avoid being carried backward. Now the resistance which
they experience and all its attendant effects are only those which
they create for themselves, and which they would experience in exactly
the same degree were they to endeavour to move _at the same rate_
in calm water or with the current in their favour. If the current be
at the rate of ten miles an hour and they are just able to maintain
their place, they are proceeding at the rate of ten miles an hour, and
they experience the opposition due to that rate of motion; precisely
the same as they would experience if they sought to accomplish the
same rate of motion under any other circumstances. And if the current
were 100 miles an hour, they would suffer no more from en