Bottom view; tops are uniformly flat. For scale, the unusually large central "reamer" style prism, recovered from the bottom of the Baltic, is 7 3/4" in diameter; the yellow color is due to selenium added as a decolorizer, which ironically "solarized" to that color due to prolonged UV exposure. The three small hexagonal pyramid style prisms at bottom left are 3" across the flats (smaller than the common Charles W. Morgan reproduction), and the two round glasses at bottom right are Lanergan's patent, with external threads on the glass, designed to be easily replaced.

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