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This is the way to arrange a strip of paper 9 in. by 2 in. so that it has only one surface and one edge.
Gum the ends together with a half twist in the slip. If a continuous line is now drawn along the middle of the band it will traverse the whole length of the paper and finish at its starting point. Again, if a mark is made on the edge, and the finger or a pencil starting from this runs along the edge, it also will return to its starting point.
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