IN a recent letter 1 under this title, Dr. A. H. Rosenthal describes an optical illusion produced by the rotating beam from a lighthouse. We studied this phenomenon last year 2, and we think that both ...
FROM observations made on three different occasions during past few summers, I can corroborate in every detail 'convergent' sunbeams reported by J. J. Hopfield 1. Always in the late afternoon, the sun ...
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