Lighthouses - Thread

Nation’s oldest lighthouse celebrates 300th anniversary
#history - Two links

There are a few videos at the second link.

Boston Lighthouse - by Light Keeper Sally Snowman


The first keeper of Boston Light was George Worthylake, who drowned, along with his wife and daughter, when returning to the island in 1718. During the American Revolution, the original lighthouse was held by British forces and was attacked and burnt on two occasions by American forces. As the British forces withdrew in 1776, they blew up the tower and completely destroyed it. The lighthouse was eventually reconstructed in 1783, to the same 75-foot (23 m) height as the original tower. In 1856 it was raised to its present height of 98 feet (30 m) and a new lantern room was added along with a 12-sided second order Fresnel lens

Wondering how a Fresnel Lens works?