THE CANTERBURY PUZZLES
into thirteen compartments, in which twelve discs of wood (called
" frogs ") were placed in the order shown in our illustration, one
place being left vacant. The numbers 1 to 6 were painted white
and the numbers 7 to 12 black. The puzzle was to get all the
white numbers where the black ones were and
vice versa.
The
white frogs move round in one direction, and the black ones the
opposite way. They may move in any order one step at a time, or
jumping over one of the opposite colour to the place beyond, just as
we play draughts to-day. The only other condition is that when all
the frogs have changed sides, the 1 must be where the 12 now is
and the 12 in the place now occupied by 1. The puzzle was to
perform the feat in as few moves as possible. How many moves
are necessary ?
I will conclude in the words of the old writer, " These be some of
the riddles which the monks of Riddlewell did set forth and expound
each to the others in the merry days of the good Abbot David."
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