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January 19, 2017
1. From Historical Instances To Electrification
As an island nation, we in the UK are used to seeing lighthouses round our coasts, but have you ever ever stopped to contemplate after they were first built and the way they worked in these early days.
The aim of lighthouses is clearly to mark dangerous coastlines, rocks and reefs and to help navigation, especially at night or in misty situations.
The primary known warnings made to boats of hazardous rocks and shores, were fires, set at the sting of the water, but it surely was in Egypt that we first heard of precise structures being built, which used light to information ships.
The Lighthouse of Alexandria
Built on the island of Pharos, the lighthouse was commissioned by Ptolemy in 290 B.C. It took 20 years to construct, and grew to become the tallest building in existence, except for the nice Pyramid, standing at between 450 and 600 toes in peak, and was recognised as one of the Seven Wonders of the World.
It is thought to have cost around the equal of three million dollars or £2.Eight million. Its design was nothing like the slim constructions we are aware of right now. It consisted of three stages, the first being in the form of a massive field built on a 20 foot excessive stone platform. On prime of this was an eight sided tower, adopted by a cylinder that prolonged to an open cupola the place the fire burned to supply the sunshine. On its roof was a big statue, thought to be of the sea god Poseidon. The fire’s light was believed to have been projected right into a beam by the use of a large curved mirror, most likely fabricated from polished bronze. It was mentioned that ships may detect its signals up to one hundred miles away, the sunshine from the tower by evening, and the smoke from the hearth by day. This declare however appears a bit extreme.
The lighthouse turned so famous that the name “pharos” became the foundation of the phrase “lighthouse” in many languages. It stood for over 1,500 years, surviving a tsunami in 365 Advert, however earth tremors resulted in cracks forming in the structure which needed restoration. Then, a significant earthquake in the region, in the 14th century, triggered such severe injury that the construction finally collapsed.
Other early lighthouses
In medieval occasions the Iranians apparently erected large minaret towers within the mouth of the Persian Gulf to help navigation. In China, the medieval mosque at Canton also had a minaret serving as a lighthouse, and in 1165 a pagoda recognized as the Liuhe Pagoda, was inbuilt Hangzhou and acted as a lighthouse for sailors in the Qiantang River.
One of the oldest working lighthouses in Europe is Hook Lighthouse, constructed at Hook Head in County Wexford, Ireland in thirteenth century and in-built circular design. Two lighthouses, called the Pharos, were built at Dover (UK) soon after the Roman conquest of Britain. They have been constructed on two heights (the Japanese and the Western). The one on the Eastern Top nonetheless stands within the grounds of Dover Castle.
One other famous early Roman lighthouse is the Tower of Hercules, in all probability inbuilt the primary century, on a peninsula at A Coruna in north-west Spain. It was originally known because the “Farum Brigantium”, the Latin word farum being derived from the Greek pharos.
The sunshine was initially produced utilizing a wood fired system situated on the summit platform, but the lighthouse was abandoned after the Viking Invasions of 854-56. It was restored within the 14th century when the city became one of many kingdom’s largest ports, and by the 17th century it had been fitted with a dome shaped lantern. More restoration was accomplished within the early 18th century, stone island green garment dyed parka in david tc and in 1847, a system utilizing Fresnel lenses (see later) was put in. It was electrified in 1926, with a beam visible for as much as 32 nautical miles and is the oldest Roman lighthouse in use in the present day.
Some early lighthouses used wick lamps as a light supply and often the beam might only journey just a few miles. The Argand hollow wick lamp and parabolic reflector were developed in Europe around 1781, whereas in the USA, whale oil was used with wicks till the Argand system was introduced round 1810,which was then later changed with Colza oil (much like rapeseed oil), lard oil after which Kerosene.
The Fresnel lens
In 1822 a Frenchman, named Augustin Fresnel, discovered how to extend the light depth utilizing prisms, and the primary Fresnel lens was installed in 1822 in the Cordouan lighthouse in the mouth of the Gironde estuary. This gentle could possibly be seen from 20 miles or 32 km away. By the 1860s, low-gentle-loss Fresnel lenses, a lot larger than the original ones, were in use in lighthouses stone island green garment dyed parka in david tc around Britain and France, their use shortly extending to Italy and additional afield to Australia and America.