Lighthouse lantern room with Fresnel lens

Autor:

Adolphe Ganot

Credit:

Downloaded from Adolphe Ganot (1872) Natural Philosophy for General Readers and Young Persons (translated with permission from Ganot's Cours Élémentaire de Physique by Edmund Atkinson), D. Appleton & Co., New York, p.329, fig.258 on Google Books

Krótki link:

https://plwiki.pl/b/9e4c5

źródło:

Wikimedia Commons

Wymiary:

642 x 892 Pixel (153413 Bytes)

Opis:

Cutaway drawing of a lighthouse lantern room from mid 1800s showing the Fresnel lens. Source says this was a lens of the 'largest size', made by M. Souter and exhibited at the Paris Universal Exposition in 1855. The cylindrical lens with 8 faces stood 10 feet high. A clockwork mechanism (M), driven by weight (P), slowly turns the entire lamp-lens assembly (A,B) on six rollers. This system, invented by Augustin-Jean Fresnel, scans the 8 beams from the lens around the whole horizon. The resulting regularly flashing light seen by mariners served to distinguish the lighthouse from stars or shore lights. Alterations: removed caption.

Licencja:

Public domain

Komentarz do licencji:

Public domain - Published in USA before 1923.