1. From Ancient Times To Electrification
As an island nation, we in the UK are used to seeing lighthouses around our coasts, but have you ever stopped to consider once they have been first constructed and the way they labored in these early days.
The aim of lighthouses is obviously to mark dangerous coastlines, rocks and reefs and to aid navigation, particularly at night time or in misty situations.
The primary recognized warnings made to boats of hazardous rocks and shores, have been fires, set at the edge of the water, but it was in Egypt that we first heard of precise constructions being constructed, which used gentle to information ships.
The Lighthouse of Alexandria
Constructed on the island of Pharos, the lighthouse was commissioned by Ptolemy in 290 B.C. It took 20 years to construct, and became the tallest building in existence, except for the nice Pyramid, standing at between 450 and 600 feet in height, and was recognised as one of many Seven Wonders of the World.
It’s thought to have value across the equal of three million dollars or £2.Eight million. Its design was nothing just like the slim constructions we’re conversant in right now. It consisted of three levels, the primary being within the form of an enormous field constructed 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 where the hearth burned to supply the sunshine. On its roof was a large statue, thought to be of the sea god Poseidon. The fire’s gentle was believed to have been projected right into a beam by way of a big curved mirror, most likely manufactured from polished bronze. It was stated that ships might detect its indicators as much as one hundred miles away, the sunshine from the tower by night time, and the smoke from the fireplace by day. This declare nonetheless appears slightly extreme.
The lighthouse turned so well-known that the title “pharos” turned the foundation of the phrase “lighthouse” in lots of languages. It stood for over 1,500 years, surviving a tsunami in 365 Advert, however earth tremors resulted in cracks forming within the construction which wanted restoration. Then, a serious earthquake within the area, within the 14th century, prompted such extreme injury that the construction ultimately collapsed.
Different early lighthouses
In medieval instances the Iranians apparently erected giant minaret towers within the mouth of the Persian Gulf to assist navigation. In China, the medieval mosque at Canton additionally had a minaret serving as a lighthouse, and in 1165 a pagoda recognized because the Liuhe Pagoda, was inbuilt Hangzhou and acted as a lighthouse for sailors within the Qiantang River.
One of many oldest working lighthouses in Europe is Hook Lighthouse, constructed at Hook Head in County Wexford, Eire in thirteenth century and inbuilt circular design. Two lighthouses, known as the Pharos, were built at Dover (UK) soon after the Roman conquest of Britain. They were constructed on two heights (the Eastern and the Western). The one on the Japanese Top nonetheless stands within the grounds of Dover Castle.
One other well-known early Roman lighthouse is the Tower of Hercules, most likely built in the first century, on a peninsula at A Coruna in north-west Spain. It was originally known as the “Farum Brigantium”, the Latin word farum being derived from the Greek pharos.
The sunshine was initially produced utilizing a wooden fired system situated on the summit platform, but the lighthouse was abandoned after the Viking Invasions of 854-fifty six. It was restored within the 14th century when the city turned one of many kingdom’s largest ports, and by the seventeenth century it had been fitted with a dome Stone Island Vests formed lantern. More restoration was completed within the early 18th century, and in 1847, a system utilizing Fresnel lenses (see later) was put in. It was electrified in 1926, with a beam seen 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 source and often the beam might solely journey a number of miles. The Argand hollow wick lamp and parabolic reflector have been developed in Europe round 1781, whereas within the USA, whale oil was used with wicks till the Argand system was launched around 1810,which was then later changed with Colza oil (similar to rapeseed oil), lard oil after which Kerosene.
The Fresnel lens
In 1822 a Frenchman, named Augustin Fresnel, discovered how to extend the sunshine depth utilizing prisms, and the primary Fresnel lens was put in in 1822 within the Cordouan lighthouse within the mouth of the Gironde estuary. This mild could be seen from 20 miles or 32 km away. By the 1860s, low-mild-loss Fresnel lenses, much bigger than the unique ones, had been in use in lighthouses round Britain and France, their use shortly extending to Italy and additional afield to Australia and America.
To create the flashing effect, designers had to come up with a way of making the lens revolve. This was done utilizing a rotating stand with a clockwork mechanism with descending weights on cables. The keeper periodically cranked up the burden to the highest of the lighthouse and because it descended, the lens revolved. The flashing effect was achieved each time a section of the rotating lens passed between the lamp and the observer. The speed of rotation decided the frequency of the flash and made it potential for every lighthouse to have its personal recognisable sample.
The appearance of electricity
Across the flip of the twentieth century, acetylene gasoline (electricity and carbide) started changing kerosene, and round 1910 many lighthouses started utilizing the intelligent system referred to as the Dalen Solar Valve, invented by the Swede, Gustav Dalen. The valve opened and closed the fuel provide stone island cotton fleece zip sweatshirt to the lamp in keeping with how a lot sunlight it obtained, so the lights might be turned on routinely at dusk and off at daybreak. Dalen additionally came upon methods to retailer the gasoline in tanks and to interrupt its stream, inflicting the sunshine to flash. Dalen’s innovations resulted in financial savings in gasoline and upkeep, because the lamps solely wanted servicing twice a yr.
As electricity grew to become obtainable, the clockwork mechanisms within the lighthouses have been changed by electric motors, with 100W bulbs offering the sunshine supply, and electronically operated fog indicators have been added. With all this electrification and automation, lighthouse keepers have been sadly out of date and from the 1980 they grew to become superfluous to necessities. The final lighthouse within the UK to be automated was North Foreland in Kent, in 1998.
Many Fresnel lenses have been replaced by rotating aerodrome beacons which require much less upkeep. The system of rotating lenses has in some instances been changed by a excessive depth mild that emits quick flashes, much like the obstruction lights used to warn aircraft of tall buildings.
Recent innovations include Vega Lights, (lighthouse beacons providing a range of up to 22 nautical miles with a one hundred Watt lamp). They’ll function in distant, photo voltaic-powered places, on unattended websites, and require upkeep only once a year. There are in the region of 600 of these in operation around the world.
Technology moves on, and as new innovations such as GPS make navigation easier and safer, it may be tempting to think that lighthouses have had their day.
Personally I’d prefer to have a reliable backup to my GPS, and there’s nothing so comforting on your first ever night watch below sail, than to see the beam of a lighthouse shining by the darkness, to count the flashes and know that you are where you should be.
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