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  1. Lighthouses This is a presentation about the presence of lighthouses in our world. You will learn about where they are located, why we use them, and see their location and their beauty. 4/15/11

  2. What is a Lighthouse? • A lighthouse is a tower on or near the shore of an ocean, harbor, or river. There is a lantern room on top that holds the lens. This is where the light shines out. The lens shines a bright light to warn ships about dangers like rocks or sandbars. It can also mark the entrance to a river or inlet. • For more information about lighthouses, take a look at Dan’s Lighthouse Page:

  3. History of Lighthouses • Lighthouses date back to ancient Egypt, where priests maintained the beacon fires. For about 1,500 years, the lighthouse of Pharos, built in the 3rd century, guided ships into the Nile. It was lighted by a wood fire and showed smoke by day and a glow by night. • In the United States, the tower for the Boston Light on Little Brewster Island was built in 1716; the first structure of the Brant Point Light, Nantucket, was built in 1746, and the Beavertail Light on ConanicutIsland,Narragansett Bay, was erected in 1749.

  4. For More Information… • Check out this video link on Alexandria: the Pharos Lighthouse: •

  5. How do Lighthouses Work? • The “Everyday Mysteries” website is quoted as saying: “The design of the lighthouse light as we know it today, originated at the beginning of the 18th Century. The French inventor Augustin Fresnel had correctly deduced that light was pure energy that traveled in waves, and he then spent his life developing lenses and reflectors that could capture and concentrate light. The first lighthouse optics that he designed combined highly polished prisms with an array of lenses that captured light and concentrated it back into a main beam. The design was concentric in arrangement, funneling the light into a beam that was many times brighter than its source. This light could be seen for more than 20 miles. Fresnel’s design of concentric glass rings to concentrate light is still used today in the production of automobile headlights, traffic signals and projectors. Many of today’s lighthouses have a system of rotating lenses, and the newer ones flash off and on as a way of conserving energy.” •

  6. The Fresnel Lens • This is the name given to the lens in most lighthouses today. For a short video on how these lenses work, watch this! •

  7. Lighthouses of Today • You can visit lighthouses in most all states where working and non-working lighthouses exist. Check out their locations: • New England Lighthouses: • North Carolina’s Lighthouses: • Lighthouses of Illinois: • Many other locations:

  8. Webcams • Here are a couple of webcams atop a lighthouse. See it live for yourself! • Eagle Harbor Webcam: • 8 different locations to see live!

  9. Legendary Lighthouses • For some chilling stories about legendary lighthouses, check out these scary tales of haunted lighthouses in the world: •

  10. References • • • • • • • • • • By Carol Minarik • 4/15/11