e, indeed, but a very appreciable amount. The amount of the
displacement, or, roughly speaking, of the illusion, increases as the
larger square is made larger and the smaller one smaller; or, put in a
sentence, the amount varies directly with the ratio of the smaller to
the larger square side.

Finding such an unmistakable illusion by this method, Mr. B. thought
that if it could be tested by an appeal to people generally, it would
be of great gain. It occurred to him that the way to do this would be
to reverse the conditions of the experiment in the following way: He
prepared the figures given in Plate I, in which the two squares are
made of suitable relative size, a line is drawn between them, and a
point on the line is plainly marked. This he had printed in a weekly
journal, and asked the readers of the journal to get their friends,
after merely looking at the figure (i. e., without knowing the result
to be expected), to say--as the reader may now do before reading
further--whether the point on the line (Plate I) is in the middle or
not; and if not, in which direction from the true middle it lies. The
results from hundreds of persons of all manner of occupations, ages,
and of both sexes, agree in saying that the point lies too far toward
the larger square. In reality it is in the exact middle. This is just
the opposite of the result of the experiments in the laboratory, where
the conditions were the reverse, i. e., to find the middle as it
appears to the eye. Here, therefore, we have a complete confirmation
of the illusion; and it is now fully established that in all cases in
which the conditions of this experiment are realized we make a
constant mistake in estimating distances by the eye.[6]

[Footnote 6: In redrawing the figure on a larger sheet (which is
recommended), the connecting line may be omitted, only the mid-point
being marked. Some get a better effect with two circles, the
intervening distance being divided midway by a dot, as in Plate II.]

For instance, if a town committee wish to erect a statue to their
local hero in the public square, and if on two opposite sides of the
square there are buildings of very different heights, the statue
should not be put in the exact middle of the square, if it is to give
the best effect from a distance. It should be placed a little toward
the smaller building. A colleague of the writer found, when this was
first made public, that the pictures in his house had actually