The Second Order Fresnel Lens Seeing The Light

Home Back

Application

The Second Order lens was used in seacoast and warning lights to mark headlands, dangerous oceanic shoals, rocks or reefs. It was used quite frequently in the Great Lakes Lights, on islands, and in marking sounds. Two of the Great Lakes lights that were outfitted with this order of lens were White Shoal & Grosse Point.

Specifications


Lens height: 81.46"
Focal length:  27.6"
Weight of assembly:  3,530 lbs
Relative brightness (over sixth order): 11.54x
Useful range:  Up to 20 nautical miles
Number in US Lighthouses in 1884:  19
Number in US Lighthouses in 1922: 26
Oil consumption per hour 17.5 oz.

References

Annual Report of the Lighthouse Board, 1884
The United States Lighthouse Service
, Dept of Commerce, 1915
Aids to Navigation Manual, US Coast Guard, 1945
Comparative Table of Lens Orders, Mabel A. Baiges, 1988
Letter from Al & Helen Gademsky, 07/02/01

Terry Pepper. This page updated 12/02/2007

Home

Back