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Here is another unusual lens. The combination of a
bivalve lens with a more traditional lens panel is a type of lens that few people have
seen. The characteristic of this lens was alternating red and white flashes over a 20
second period (.5 second red flash, 9.5 second eclipse, .5 second white flash, 9.5 second
eclipse). As this lens rotated, you would have seen alternating red and white flashes as
each panel aligned with your eye. The bivalve panel was necessary because of the red
characteristic. The red actually absorbs some of the light, so a stronger lens is needed
to compensate. This lens was installed sometime prior to 1917 and may have been removed in
1978. |