1. From Historic 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 after they had been first built and the way they labored in those early days.
The aim of lighthouses is obviously to mark harmful coastlines, rocks and reefs and to aid navigation, especially at evening or in misty circumstances.
The primary identified warnings made to boats of hazardous rocks and shores, had been fires, set at the edge of the water, but it surely was in Egypt that we first heard of precise buildings being built, which used gentle 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 turned the tallest constructing in existence, aside from the nice Pyramid, standing at between 450 and 600 ft in peak, and was recognised as one of the Seven Wonders of the World.
It is thought to have price around the equivalent of three million dollars or £2.Eight million. Its design was nothing like the slim structures we are aware of at present. It consisted of three stages, the primary being within the shape of a massive box built on a 20 foot excessive stone platform. On prime of this was an eight sided tower, followed by a cylinder that extended to an open cupola the place the fireplace burned to offer the light. 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 way of a big curved mirror, in all probability made from polished bronze. It was said that ships might detect its indicators up to 100 miles away, the sunshine from the tower by night time, and the smoke from the fireplace by day. This declare nevertheless appears a little bit extreme.
The lighthouse grew to become so famous that the name “pharos” grew to become the basis of the word “lighthouse” in many languages. It stood for over 1,500 years, surviving a tsunami in 365 Advert, but earth tremors resulted in cracks forming within the construction which needed restoration. Then, a serious earthquake in the area, in the 14th century, triggered such extreme harm that the structure eventually collapsed.
Different early lighthouses
In medieval occasions the Iranians apparently erected giant minaret towers within 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 recognized because the Liuhe Pagoda, was built in 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, Eire in 13th century and built in circular design. Two lighthouses, referred to as the Pharos, were constructed at Dover (UK) quickly after the Roman conquest of Britain. They were constructed on two heights (the Japanese and the Western). The one on the Eastern Top still stands within the grounds of Dover Castle.
One other famous early Roman lighthouse is the Tower of Hercules, in all probability in-built the primary century, on a peninsula at A Coruna in north-west Spain. It was initially identified 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, but the lighthouse was abandoned after the Viking Invasions of 854-56. It was restored in 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 shaped lantern. More 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 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 light source and often the beam may only travel a number of miles. The Argand hollow wick lamp and parabolic reflector were developed in Europe around 1781, whereas within the USA, whale oil was used with wicks until the Argand system was introduced round 1810,which was then later replaced with Colza oil (much like rapeseed oil), stone island jumper and shorts lard oil after which Kerosene.
The Fresnel lens
In 1822 a Frenchman, named Augustin Fresnel, found out how to increase the sunshine intensity utilizing prisms, and the first Fresnel lens was installed in 1822 within the Cordouan lighthouse within the mouth of the Gironde estuary. This light may very well be seen from 20 miles or 32 km away. By the 1860s, low-light-loss Fresnel lenses, a lot larger than the unique ones, were in use in lighthouses round Britain and France, their use rapidly extending to Italy and additional afield to Australia and America.
To create the flashing impact, designers had to provide you with a means of creating the lens revolve. This was accomplished using 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 attainable for each lighthouse to have its personal recognisable sample.
The advent of electricity
Across the turn of the twentieth century, acetylene gas (electricity stone island jumper and shorts and carbide) started changing kerosene, and round 1910 many lighthouses started using the intelligent system referred to as the Dalen Solar Valve, invented by the Swede, Gustav Dalen. The valve opened and closed the gasoline supply to the lamp in line with how much sunlight it obtained, so the lights may very well be turned on mechanically at dusk and off at daybreak. Dalen also came upon the right way to store the gasoline in tanks and to interrupt its movement, inflicting the sunshine to flash. Dalen’s inventions resulted in savings in fuel and upkeep, as the lamps solely needed servicing twice a yr.
As electricity grew to become obtainable, the clockwork mechanisms in the lighthouses have been changed by electric motors, with 100W bulbs offering the light supply, and electronically operated fog signals have been added. With all this electrification and automation, lighthouse keepers had been sadly out of date and from the 1980 they turned superfluous to requirements. The final lighthouse in the UK to be automated was North Foreland in Kent, in 1998.
At the moment
Many Fresnel lenses have been changed by rotating aerodrome beacons which require less upkeep. The system of rotating lenses has in some cases been changed by a excessive intensity light that emits short flashes, much like the obstruction lights used to warn aircraft of tall buildings.
Recent improvements include Vega Lights, (lighthouse beacons offering a range of as much as 22 nautical miles with a a hundred Watt lamp). They’ll function in distant, photo voltaic-powered locations, on unattended sites, and require upkeep only as soon as a 12 months. There are within the region of 600 of those in operation around the globe.
Know-how strikes on, and as new innovations such as GPS make navigation simpler and safer, it could also be tempting to assume that lighthouses have had their day.
Personally I’d prefer to have a reliable backup to my GPS, and there is nothing so comforting in your first ever evening watch below sail, than to see the beam of a lighthouse shining by way of the darkness, to count the flashes and know that you are the place try to be.
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