eptionally good seeing they have, however, been seen and
drawn as finer and sharper lines.

"The visibility of the lines was, however, confirmed by so many
observers of known integrity, and from so many different parts of the
world, that the objectors were at last compelled to abandon the position
they had occupied. Then a new theory was started, viz. that the lines
were actually seen but did not actually exist, being really optical
illusions arising from the apparent integration, or running together in
linear form, of various small disconnected markings which were viewed
from beyond the distance of clear seeing.

"The manner in which it was sought to prove the correctness of this
theory appeared to me at the time (and still does so) as most weak and
fallacious, and certain experiments I made only strengthened that
opinion. However, scientific people accepted it as proof.

"In making this experiment schoolboys were seated in rows at different
measured distances from a map of Mars, which they were told to copy. The
map showed all the well-known dark patches and markings, but no fine
lines. About the places where some of those lines should have been,
dots, curls, wisps, &c., were inserted at irregular distances, and not
always exactly where the lines should have been shown. The inevitable
result was that the boys who were too far away to see clearly saw these
small markings as continuous straight lines, and so drew them. In the
circumstances they could not do otherwise; for if sufficient marks were
inserted nearly in alignment, they would necessarily produce the effect
of lines.

"These drawings were then acclaimed as _proving_ that the lines seen on
Mars were only discrete markings viewed from beyond the distance of
clear seeing, and that the network of lines seen and drawn by so many
skilled and careful observers of Mars had no actual existence upon the
planet. Thus all their work was completely discredited.

"Experiments like these could not possibly prove any such thing, because
it would be easy to insert in a map various markings which, when viewed
from a distance, would appear to form almost any design that one might
choose to depict. Any desired effect might thus be obtained; and I have
seen many pictures so formed in which the illusion was perfect. When
viewed from a distance each appeared to be a picture of something
entirely different from what was seen when it was viewed from a near
standpoint.

"The lin