The Fresnel lighthouse lens used a large lamp at the focal plane ... had been improvements over the open fires or candles in lantern rooms. Still, they could trap only a small percentage of ...

Inside a glass bottle, the crew found a letter written with quill and ink detailing the installation of a new lantern and lens, as well as the names of the engineers and lighthouse keepers.

The problem is that in those days, a lighthouse was an oil lamp, a concave mirror, and an ordinary lens. This made the lighthouses difficult to spot. Napoleon started the Commission of Lighthouses ...