Download
lighthouses n.
Skip this Video
Loading SlideShow in 5 Seconds..
Lighthouses PowerPoint Presentation
Download Presentation
Lighthouses

Lighthouses

654 Views Download Presentation
Download Presentation

Lighthouses

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Lighthouses By Peter D Aberdeen High School, 1999

  2. Lighthouse History • First lighthouses -found around Mediterranean Sea -consisted of fires on top of coastal hills • First traditional lighthouse structure -Pharos light of Alexandria constructed around 280 B.C. 280 feet tall -reflectors contained wood fire -could be seen for 35 miles

  3. Lighthouse History- 2 • Ancient Lighthouses -Portus, Italy 46 A.D. -Boulongne, France -Dover, England -Genoa, Italy 1139 -Leghorn 1304 • First in U.S. -Boston Light near Boston Harbor, 1716

  4. Lighthouse History - 3 • U.S. lights maintained and upkept by U.S. Coast Guard since July 1, 1939. • Worldwide, more than 30,000 lights today • First lightship stationed in Thames estuary in 1732

  5. Fresnel Lens • First constructed in 1822 by French physicist A. Fresnel • Uses concentric rings of glass prisms to bend and focus light into a narrow beam • Often as tall as twelve feet

  6. Concord Point Lighthouse

  7. Concord Point Light - 2 • Built in 1827 at the mouth of the Susquehanna River in Havre De Grace • 36 foot tower, originally built with tin reflector, upgraded to fresnel lens in 1854 • Decommissioned in 1975 Link to information on Concord Point Lighthouse and other lighthouses