The puzzle was to cut the two shoes (including the hoof contained within
the outlines) into four pieces, two pieces each, that would fit together
and form a perfect circle. It was also stipulated that all four pieces
should be different in shape. As a matter of fact, it is a puzzle based
on the principle contained in that curious Chinese symbol the Monad.
(See No. 158.)
[Illustration]
The above diagrams give the correct solution to the problem. It will be
noticed that 1 and 2 are cut into the required four pieces, all
different in shape, that fit together and form the perfect circle shown
in Diagram 3. It will further be observed that the two pieces A and B of
one shoe and the two pieces C and D of the other form two exactly
similar halves of the circle--the Yin and the Yan of the great Monad. It
will be seen that the shape of the horseshoe is more easily determined
from the circle than the dimensions of the circle from the horseshoe,
though the latter presents no difficulty when you know that the curve of
the long side of the shoe is part of the circumference of your circle.
The difference between B and D is instructive, and the idea is useful in
all such cases where it is a condition that the pieces must be different
in shape. In forming D we simply add on a symmetrical piece, a
curvilinear square, to the piece B. Therefore, in giving either B or D a
quarter turn before placing in the new position, a precisely similar
effect must be produced.