These diagrams show how the upper triangle is divided into five parts, which can be rearranged to form the equilateral triangle below.
The originator of this ingenious novelty says, “The method of construction is not shown, but its application is general, and the result is easily verified by measurement.”
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No. LXVI
This is an arrangement of the twenty-seven counters in nine rows, six in a row, within the borders of an equilateral triangle.
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No. LXVII
All the cards of one colour, when placed alternately, can be brought together in four moves, two at a time, thus—