1. From Historic Occasions To Electrification
As an island nation, we within the UK are used to seeing lighthouses round our coasts, but have you ever stopped to contemplate when they had been first constructed and the way they worked in those early days.
The aim of lighthouses is obviously to mark dangerous coastlines, rocks and reefs and to assist navigation, particularly at evening or in misty situations.
The primary identified warnings made to boats of hazardous rocks and shores, had been fires, set at the sting of the water, but it was in Egypt that we first heard of actual constructions 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 build, and became the tallest building in existence, apart from the great Pyramid, standing at between 450 and 600 toes in top, and was recognised as one of the Seven Wonders of the World.
It is thought to have value around the equivalent of three million dollars or £2.8 million. Its design was nothing like the slim structures we’re familiar with at this time. It consisted of three phases, the primary being within the form of an enormous field constructed on a 20 foot high stone platform. On top of this was an eight sided tower, followed by a cylinder that extended to an open cupola where the fire burned to offer the sunshine. On its roof was a big statue, thought to be of the sea god Poseidon. The fire’s mild was believed to have been projected right into a beam by the use of a large curved mirror, in all probability made from polished bronze. It was said that ships may detect its signals up to a hundred miles away, the sunshine from the tower by night, and the smoke from the hearth by day. This claim however appears just a little excessive.
The lighthouse grew to become so famous 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, however earth tremors resulted in cracks forming in the structure which wanted restoration. Then, a major earthquake in the area, in the 14th century, caused such extreme damage that the structure ultimately collapsed.
Different early lighthouses
In medieval occasions the Iranians apparently erected massive minaret towers in the mouth of the Persian Gulf to aid navigation. In China, the medieval mosque at Canton additionally had a minaret serving as a lighthouse, and in 1165 a pagoda identified as the Liuhe Pagoda, was inbuilt Hangzhou and acted as a lighthouse for sailors within the Qiantang River.
One of the oldest working lighthouses in Europe is Hook Lighthouse, constructed at Hook Head in County Wexford, Ireland in 13th century and inbuilt circular design. Two lighthouses, called the Pharos, had been constructed at Dover (UK) soon after the Roman conquest of Britain. They have been constructed on two heights (the Eastern and the Western). The one on the Eastern Peak nonetheless stands in the grounds of Dover Castle.
Another famous early Roman lighthouse is the Tower of Hercules, in all probability in-built the first century, on a peninsula at A Coruna in north-west Spain. It was originally recognized because the “Farum Brigantium”, the Latin phrase farum being derived from the Greek pharos.
The sunshine was originally produced using a wood fired system positioned on the summit platform, however the lighthouse was abandoned after the Viking Invasions of 854-56. It was restored in the 14th century when the town grew to become one of many kingdom’s largest ports, and by the 17th century it had been fitted with a dome shaped lantern. Extra restoration was completed within the early 18th century, and in 1847, a system utilizing Fresnel lenses (see later) was installed. It was electrified in 1926, with a beam visible for as much as 32 nautical miles and is the oldest Roman lighthouse in use at the moment.
Some early lighthouses used wick lamps as a gentle supply and infrequently the beam may solely journey a couple of miles. The Argand hollow wick lamp and parabolic reflector had been developed in Europe around 1781, whereas within the USA, whale oil was used with wicks until the Argand system was launched round 1810,which was then later replaced with Colza oil (just like rapeseed oil), lard oil and then Kerosene.
The Fresnel lens
In 1822 a Frenchman, named Augustin Fresnel, found out how to extend the sunshine intensity using prisms, and the first Fresnel lens was put in 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-light-loss Fresnel lenses, a lot larger than the unique ones, have been in use in lighthouses round Britain and France, their use quickly extending to Italy and additional afield to Australia and America.
To create the flashing impact, designers had to give you a way of constructing 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 load to the highest of the lighthouse and because it descended, the lens revolved. The flashing impact was achieved each time a segment of the rotating lens passed between the bermuda stone island lamp and the observer. The rate of rotation decided the frequency of the flash and made it doable for each lighthouse to have its own recognisable pattern.
The arrival of electricity
Around the turn of the twentieth century, acetylene fuel (electricity and carbide) began replacing kerosene, and around 1910 many lighthouses began using the intelligent device referred to as the Dalen Sun Valve, invented by the Swede, Gustav Dalen. The valve opened and closed the gas supply to the lamp in line with how a lot sunlight it acquired, so the lights may very well be turned on automatically at dusk and off at dawn. Dalen additionally discovered find out how to store the gasoline in tanks and to interrupt its move, causing the sunshine to flash. Dalen’s inventions resulted in financial savings in gasoline and upkeep, because the lamps solely wanted servicing twice a yr.
As electricity became obtainable, the clockwork mechanisms within the lighthouses have been replaced by electric motors, with 100W bulbs offering the sunshine source, and electronically operated fog alerts had been added. With all this electrification and automation, lighthouse keepers have been sadly out of date and from the 1980 they turned superfluous to necessities. The final lighthouse within the UK to be automated was North Foreland in Kent, in 1998.
Many Fresnel lenses have been changed by rotating aerodrome beacons which require less upkeep. The system of rotating lenses has in some instances been replaced by a high depth mild that emits short flashes, just like the obstruction lights used to warn aircraft of tall buildings.
Current innovations embrace Vega Lights, (lighthouse beacons offering a spread of up to 22 nautical miles with a one hundred Watt lamp). They’ll operate in remote, solar-powered locations, on unattended sites, and require maintenance only once a 12 months. There are within the area of 600 of these in operation world wide.
Expertise strikes on, and as new innovations equivalent to GPS make navigation simpler and safer, it may be tempting to assume that lighthouses have had their day.
Personally I’d choose to have a reliable backup to my GPS, and there may be nothing so comforting on your first ever night time watch beneath sail, than to see the beam of a lighthouse shining by way of the darkness, to depend the flashes and know that you are the place you need to be.
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