An Illusion of Size


IN his letter, Mr. J. Phelps1 refers to an interesting point in the manufacture of threepences, namely, their expansion in the coining press into dodecagonal steel collars. The fact that the corners of coins subsequent to 1940 are more rounded than are those of earlier ones seems to point to a change in the collars at about that date. If this is the case, it will also explain the change in the size of the coins which occurred at about the same time referred to in my letter2.


  1. 1

    Nature, 156, 269 (1945).

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  2. 2

    Nature, 156, 118 (1945).

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  3. 3

    Nature, 155, 672 (1945).

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HARTRIDGE, H. An Illusion of Size. Nature 156, 636 (1945).

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