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Companion Story to Western U.P. Lighthouses
Sun Valve. The sun valve was designed to automatically turn
on acetylene gas on when the temperature dropped at night and turn it
off when the temperature rose during the day. The valve worked by the
contraction of dissimilar metals, which opened or closed the valve.
Lewis Lamps. Patented by Winslow Lewis, a Cape Cod sea captain, in
1812, this lamp essentially combined a whale oil lamp with a parabolic
reflector. They were very poorly made and were a “rip-off” of a
European lamp. The reflectors were out of round and their silvered
surface rubbed off when polished. They required constant repair.
Regardless of the problems, they were adopted for U.S. lights under an
exclusive agreement with Stephen Pleasonton, the fifth auditor of the
U.S. Treasury who ran the Lighthouse Service until 1852.
Fresnel Lens. This remarkable lens was developed by French physicist
Augustine Fresnel starting in 1819. By 1823, he produced a lens
infinitely superior to the Lewis system, which quickly became the
European standard. Essentially Fresnel circled the light source with a
series of prisms that captured virtually all of the available light and
focused it into a narrow beam. Traditionally there were six orders or
sizes of lens, 1st to 6th (including a 3rd and a 3-1/2). First was the
largest, perhaps a dozen feet tall and the sixth the smallest. First
order lenses where never used on the Great Lakes and only five 2nd
orders were ever used. Despite their effectiveness, Fresnel lenses
were not installed in the U.S. until the 1850s.
– by Frederick Stonehouse
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