he same height, yet the furthest one appears to be much
taller and bigger altogether than the middle one, and the middle one
than the nearest. This result is obtained by suggesting distance as
separating the right-hand figure from us, whilst giving it exactly the
same height as the others. This seems to me to be a simple case of an
illusion of increased size produced by a suggestion of increased
distance when all the time there is equality in size--as in the case
of the moon on the horizon compared with the moon overhead. It would
be interesting to see an attempt on the part of a competent painter to
produce in this way (which is, I believe, Nature's way) the illusion
of increased size in a low-lying moon without really increasing the
visual size of his painted moon as compared with one in another
picture (to be painted by him) representing the moon bright, clear and
small, overhead.

[Illustration: Plate V.--Drawing of three figures--Lord Lansdowne, Mr.
Lloyd George, and Mr. Asquith--showing how an illusion of size may be
produced in a picture. The figure of Mr. Asquith is of the same actual
vertical measurement as that of Lord Lansdowne, viz. two inches and
one eighth. Yet owing to the position in which the three figures are
placed and the converging lines--suggesting perspective--the drawing
of Mr. Asquith does not merely represent a much taller man than does
that of Lord Lansdowne, but actually gives the impression, at first
sight, that the little black figure representing Mr. Asquith is longer
and bigger altogether than that representing Lord Lansdowne. Yet the
figures are of the same dimensions. It is owing to illusion of the
same nature that the disc of the low moon appears larger than that of
the high moon.]

The theatrical scene-painter has another kind of difficulty with the
low moon and the setting sun. He can never be right for more than one
row of seats--one distance--in the theatre. Here there is no
peep-hole, no frame or picture-plane. The observer is _in_ the
picture. If the moon is represented by an illuminated disc of one foot
in diameter, it will, when looked at at a distance of 115 feet, have
the same visual size as the moon itself, but if your seat is nearer
the scene it will look too large, if further off it will look too
small. There is no getting over this difficulty, as the standard of
actual Nature is set up on the stage by the men and women appearing on
it at a known distance. It used to be