n arises from the circumstance that the scene displayed
below and around the balloon is judged by the eye from the experience of
more familiar scenes. The horizon is depressed, but so little that the
eye cannot detect the depression, especially where the boundary of the
horizon is irregular. It is here that the text-book pictures mislead;
for they show the depression as far too great to be overlooked, setting
the observer sometimes about two thousand miles above the sea-level. The
eye, then, judges the horizon to be where it usually is--on the same
level as the observer; but looking downwards, the eye perceives, and at
once appreciates if it does not even exaggerate, the great depth at
which the earth lies below the balloon. The appearance, then, as judged
by the eye, is that of a mighty basin whose edge rises up all round to
the level of the balloon, while its bottom lies two or three miles or
more below the balloon.

The zetetic faithful reason about this matter as though the impressions
of the senses were trustworthy under all conditions, familiar or
otherwise; whereas, in point of fact, we know that the senses often
deceive, even under familiar conditions, and almost always deceive under
conditions, which are not familiar. A person, for example, accustomed to
the mist and haze of our British air, is told by the sense of sight,
when he is travelling where a clearer atmosphere prevails, that a
mountain forty miles from him is a hill a few miles away. On the other
hand, an Italian travelling through the Highlands is impressed with the
belief that all the features of the scenery are much larger (because he
supposes them much more remote) than they really are. A hundred such
instances of deception might easily be cited. The conditions under which
the aeronaut observes the earth are certainly less familiar than those
under which the Briton views the Alps and Apennines, or the Italian
views Ben Lomond or Ben Lawers. It would be rash, therefore, even if no
other evidence were available, to reject the faith that the earth is a
globe because, as seen from a balloon, it looks like a basin. Indeed, to
be strictly logical, the followers of Parallax ought on this account to
adopt the faith that the earth is not flat, but basin-shaped, which
hitherto they have not been ready to do.

We have seen that Parallax describes a certain experiment on the Bedford
Level, which, if made as he states, would have shown certainly that
somethin