propounded the theory
that matter may consist of vortex rings in a fluid that fills all space,
and by a development of the hypothesis he was able to explain chemical
combination.

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[Illustration]

164.--THE POTATO PUZZLE.

Take a circular slice of potato, place it on the table, and see into how
large a number of pieces you can divide it with six cuts of a knife. Of
course you must not readjust the pieces or pile them after a cut. What
is the greatest number of pieces you can make?

[Illustration:

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/ \ /\ / \
/ \ 4 \/ 5\/ 6 / \
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\ 7\/ 8\/ 9\/10 /
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The illustration shows how to make sixteen pieces. This can, of course,
be easily beaten.

165.--THE SEVEN PIGS.

[Illustration]

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