How
it was |
What Happened  |
HOW IT IS TODAY!
 |
WCID 12 found
Designer and lens preservationist Dan
Spinella in Florida and arranged for him to
"Create" the Lens for the new WCID 12 Kemah,
Texas Water Tower/Lighthouse. Here is a
brief summary of the Fresnel lens that was
installed in the Kemah Lighthouse. |
Kemah Water-tower Lighthouse,
Texas 3rd Order Rotating Fresnel Lens
The
lens is a 3rd order rotating Fresnel lens replica.
It was modeled after the historic Fresnel lenses that
were common in U.S. lighthouses from the mid 1800’s to
the early 1900’s. Some lighthouses still retain
their Fresnel lenses but most are in museums. The
lens was invented by the French physicist Augustin
Fresnel in 1819. These lenses come in 6 sizes also
know as orders, 6th order (smallest lens) to 1st order
(largest lens). The production of these lenses
stopped in the early 1900’s. Texas 3rd Order Rotating Fresnel Lens
The lens installed in the Kemah Lighthouse is a 3rd order rotating style. The lenses and prisms are machined from an optical acrylic material. Original Fresnel lenses have glass lenses and prisms. The Coast Guard values an original 3rd order lens at $750,000.00. Manufacturing the lens out of acrylic is more cost effective and can be produced for about 1/10 the cost. The frame is made of solid brass just as the historic lenses. The lens has 8 flash panels, or bulls-eyes, and produces 8 beams of light. The lens rotates approximately 1 revolution per minute and produces a flash every 7 seconds. The light source is a 1000 watt bulb that remains steady. The flash is produced by the rotation of the lens viewed from a distance as the flash panel rotates in your line of sight. The lens weighs 750 lbs. and is 6 feet tall and 4 feet in diameter. The total height is 10 feet including the pedestal.
I designed the lens. My company name is Artworks Florida www.artworks-florida.com . Augustin Fresnel’s original formulas were used to calculate the shapes and curvatures of the lenses and prisms. The lens collects light from a single source and directs it into horizontal beams. The original lenses were illuminated by oil or kerosene burning lamps. A clockwork mechanism was used to rotate the lens driven by a weight that would drop down the center of the lighthouse, very similar to a grandfather clock. The Kemah lens is rotated by an electric motor and gearbox.
by Dan Spinella
