The Fresnel Lens was a technological leap in lighthouse lighting. With a precise arrangement of glass bull's-eyes and prisms the light was concentrated into parallel rays that produced a much brighter beam from a single light source.
|1872 Diagram showing how a Fresnel Lens works|
In 1854 the Winslow Lamps in the Ocracoke Lighthouse were replaced with a fourth order Fresnel Lens.
|Ocracoke's Fresnel Lens|
There are six orders of Fresnel Lenses, based on their size and focal length. First order lenses are the largest.
This month's Ocracoke Newsletter is a brief history of Howard's Pub. You can read it here: https://www.villagecraftsmen.com/news082117.htm.