Porer lighthouse, built in 1890

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 © Technisches Museum Wien, Photo: Peter Sedlaczek
“Model dedicated by the imperial & royal maritime authority in Trieste 1890” – the base inscription reveals the pride felt for the comprehensive and modern equipment of this navigational aid.

The 35 m lighthouse at Porer was built in 1833. It stands on a rock a mere 80 m wide located 2.5 km south-west of the coastal town of Premantura. Besides a beacon light the navigational aid in southern Istria also features an electric and an optical telegraph station used to indicate the wind speed and wind direction.

Most light beacons are equipped with plano-convex glass lenses. They bundle the light, which radiates the light source. In 1819/20 Augustin Jean Fresnel designed a dioptric (refracting) lens for concentrating rays of light which significantly reduced the overall weight of the lens. The first lens he had built in 1825 comprised catadioptric glass prisms above and below the dioptric lens which served to break and reflect the light simultaneously.

Light beacons are mounted in a rotatable arrangement and are manufactured as searchlight lenses and drum lenses. In searchlight lenses the light is bundled in a vertical and horizontal direction while drum lenses bundle the light in a vertical direction only. Both systems can also be used in combination.


Inv.Nr. 39931

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