1. From Historic Occasions To Electrification
As an island nation, we in the UK are used to seeing lighthouses around our coasts, however have you ever ever stopped to think about once they were first constructed and how they labored in these early days.
The purpose of lighthouses is obviously to mark dangerous coastlines, rocks and reefs and to aid navigation, particularly at night or in misty circumstances.
The first known warnings made to boats of hazardous rocks and shores, have been fires, set at the edge of the water, nevertheless it was in Egypt that we first heard of precise buildings being built, which used gentle to guide 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 became the tallest building in existence, aside from the good Pyramid, standing at between 450 and 600 feet in peak, and was recognised as one of the Seven Wonders of the World.
It’s thought to have value across the equivalent of three million dollars or £2.Eight million. Its design was nothing like the slim structures we’re acquainted with in the present day. It consisted of three phases, the first being in the shape of an enormous field constructed on a 20 foot high stone platform. On prime of this was an eight sided tower, adopted by a cylinder that prolonged to an open cupola the place 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 light was believed to have been projected into a beam by means of a large curved mirror, in all probability fabricated from polished bronze. It was said that ships may detect its indicators up to a hundred miles away, the sunshine from the tower by night time, and the smoke from the fireplace by day. This declare nonetheless seems a little bit extreme.
The lighthouse became so well-known that the name “pharos” grew to become the foundation of the phrase “lighthouse” in many languages. It stood for over 1,500 years, surviving a tsunami in 365 Ad, but earth tremors resulted in cracks forming within the construction which wanted restoration. Then, a serious earthquake within the region, within the 14th century, triggered such severe damage that the structure ultimately collapsed.
Different early lighthouses
In medieval instances the Iranians apparently erected large minaret towers in the mouth of the Persian Gulf to assist navigation. In China, the medieval mosque at Canton also had a minaret serving as a lighthouse, and in 1165 a pagoda identified as the Liuhe Pagoda, was in-built 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, Ireland in 13th century and in-built circular design. Two lighthouses, referred to as the Pharos, had been constructed at Dover (UK) soon after the Roman conquest of Britain. They had been constructed on two heights (the Japanese and the Western). The one on the Japanese Peak nonetheless stands within the grounds of Dover Castle.
One other famous early Roman lighthouse is the Tower of Hercules, probably in-built the primary 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 originally produced utilizing a wooden fired system positioned on the summit platform, however the lighthouse was abandoned after the Viking Invasions of 854-fifty six. It was restored within the 14th century when the city grew to become one of many kingdom’s largest ports, and by the 17th century it had been fitted with a dome formed lantern. Extra restoration was accomplished in the early 18th century, and in 1847, a system utilizing Fresnel lenses (see later) was installed. It was electrified in 1926, with a beam seen for up to 32 nautical miles and is the oldest Roman lighthouse in use right this moment.
Some early lighthouses used wick lamps as a mild supply and often the beam may solely journey a few miles. The Argand hollow wick lamp and parabolic reflector have been developed in Europe around 1781, while in the USA, whale oil was used with wicks until the Argand system was launched around 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, came upon how to extend the light intensity utilizing prisms, and the primary Fresnel lens was installed in 1822 in the Cordouan lighthouse in the mouth of the Gironde estuary. This mild could possibly be seen from 20 miles or 32 km away. By the 1860s, low-gentle-loss Fresnel lenses, a lot larger than the unique ones, were in use in lighthouses around Britain and France, their use quickly extending to Italy and further afield to Australia and America.
To create the flashing impact, designers had to provide you with a method of constructing the lens revolve. This was performed utilizing a rotating stand with a clockwork mechanism with descending weights on cables. The keeper periodically cranked up the weight to the top of the lighthouse and because it descended, the lens revolved. The flashing effect was achieved each time a section of the rotating lens handed between the lamp and the observer. The speed of rotation decided the frequency of the flash and made it potential for each lighthouse to have its personal recognisable sample.
The advent of electricity
Around the turn of the twentieth century, acetylene gas (electricity and carbide) began replacing kerosene, and around 1910 many lighthouses began using the clever gadget referred to as the Dalen Solar Valve, invented by the Swede, Gustav Dalen. The valve opened and closed the gas provide to the lamp according to how much sunlight it received, so the lights could possibly be turned on robotically at dusk and off at dawn. Dalen additionally discovered the way to retailer the fuel in tanks and to interrupt its stream, causing the light to flash. Dalen’s innovations resulted in savings in gas and maintenance, as the lamps solely wanted servicing twice a yr.
As electricity turned accessible, the clockwork mechanisms in the lighthouses had been changed by electric motors, with 100W bulbs offering the light supply, and electronically operated fog indicators have been added. With all this electrification and automation, stone island blue hooded waxed field jacket lighthouse keepers had been sadly out of date and from the 1980 they turned superfluous to requirements. The final lighthouse within the UK to be automated was North Foreland in Kent, in 1998.
Right this moment
Many Fresnel lenses have been changed by rotating aerodrome beacons which require much less upkeep. The system of rotating lenses has in some circumstances been changed by a high intensity gentle that emits short flashes, much like the obstruction lights used to warn aircraft of tall buildings.
Current improvements embrace Vega Lights, (lighthouse beacons providing a spread of as much as 22 nautical miles with a a hundred Watt lamp). They will operate in distant, solar-powered locations, on unattended sites, and require upkeep solely as soon as a 12 months. There are within the region of 600 of those in operation all over the world.
Know-how strikes on, and as new improvements corresponding to GPS make navigation simpler and safer, it may be tempting to suppose that lighthouses have had their day.
Personally I’d desire to have a reliable backup to my GPS, and there may be nothing so comforting in your first ever night time watch below sail, than to see the beam of a lighthouse shining via the darkness, to depend the flashes and know that you are the place try to be.
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