28 November 2011

More on Vikings Navigated With Translucent Crystals?

National Geographic
November 13, 2011

Icelandic spar may have revealed sun's position on cloudy days, study says.



Vikings may have navigated by looking through a type of crystal called Icelandic spar, a new study suggests.

In some Icelandic sagas- embellished stories of Viking life- sailors relied on so-called sunstones to locate the sun's position and steer their ships on cloudy days. The stone would've worked by detecting a property of sunlight called polarization. Polarization is when light- which normally radiates randomly from its source- encounters something, such as a shiny surface or fog, that causes the rays to assume a particular orientation.

Due to this property, as sunlight moves through the atmosphere, the resulting polarization gives away the direction of the original source of the light.

Detecting light's polarization is a natural ability of some animals, such as bees.

In 1969, a Danish archaeologist suggested real-life Vikings might have used sunstones to detect polarized light, using the stones to supplement sundials, stars, and other navigational aids.

Since then, researchers have been probing how such a sunstone might have worked. On that point, though, the sagas were silent.

Sun-Revealing Crystal

Now, Guy Ropars, a physicist at the University of Rennes in France, has conducted an experiment with a potential Viking sunstone: a piece of Icelandic spar recently found aboard the Alderney, a British ship that sank in 1592.

In the laboratory, Ropars and his team struck the piece of Icelandic spar with a beam of partly polarized laser light and measured how the crystal separates polarized from unpolarized light.

By rotating the crystal, the team found that there's only one point on the stone where those two beams were equally strong- an angle that depends on the beam's location.

That would enable a navigator to test a crystal on a sunny day and mark the sun's location on the crystal for reference on cloudy days. On cloudy days, a navigator would only be able to use the relative brightness of the two beams.

Icelandic Spar "Ideal" for Navigating

The team then recruited 20 volunteers to take turns looking at the crystal outside on a cloudy day and measure how accurately they could estimate the position of the hidden sun. Navigators subdivide the horizon by 360 degrees, and the team found that the volunteers could locate the sun's position to within 1 degree. The results confirm "that the Icelandic spar is an ideal crystal, and that it can be used with great precision" for locating the sun, said ecologist Susanne Akesson of Sweden's University of Lund, who was not part of Ropars's research team.

In 2010 Akesson and colleagues showed how local weather conditions may have influenced how light polarizes in the sky at Arctic latitudes, something Vikings would've needed to account for in their navigation.

"But the question remains," she said, "whether [Icelandic spar] was in common use" in Viking times.

On that point, physics is also silent.






11 November 2011

Treasure hunter digs up 200 piece haul of Viking jewellery and coins

UK Mail Online

October, 27 2011

A metal detecting enthusiast unearthed 'the find of a lifetime' when he discovered a Viking treasure hoard including 200 pieces of silver jewellery.


Darren Webster dug up a 1,000-year-old casket that also held coins, hacksilver and ingots while scouring at an undisclosed location on the border between Cumbria and North Lancashire.

Experts at the British Museum in London say the find is of 'national significance'.

'It's a find of a lifetime,' said Mr Webster, from Carnforth, Cumbria.

'It's a long process having the find assessed.

'Neither me or the landowner know what will happen with it. There has been a lot of interest. I want everybody to know about the find.

'I got a good signal on my detector so I dug about 18 inches and then I saw a lead pot. It was slightly open. I could see all the coins and jewellery inside. It was a great feeling.'

Bracelets elaborately engraved with serpents, which could have been worn by a wealthy Viking leader, make up part of the discovery along with rings and an impressive stash of coins.

The haul is now being studied by experts at the British Museum who will reveal their findings in December.

Secret: Mr Webster has not revealed the location of his find - which included silver jewellery and coins - but he made it while out on a weekly expedition on the border between Cumbria and North Lancashire.

Brian Randall, chairman of the Lune Valley Metal Detecting Club, said: 'We are all thrilled for Darren and wish it was us.

'No one goes out looking for hoards but it's very nice if you do find one.'

Sabine Skae, the curator of Barrow's Dock Museum, said the new hoard will help put Cumbria and South Lakeland on the map as having an important Viking heritage.

'Over the past ten years there has been an increase in small finds and now some larger finds which is really forcing people to look at Cumbria in a new way,' said Mrs Skae.

Oxford University anthropology lecturer, Stephen Oppenheimer, said big hoards such as this paint a new picture of what Vikings were doing in England.

The discovery of big hoards break down the stereotype of Vikings just coming over here to raid our churches and take valuables back to their own country.



'Burying large amounts like this indicates they were settling here,' said Mr Oppenheimer.

Local archaeologist Steve Dickinson, of Ulverston, said the hoard was 'extremely important nationally'.

He said: 'Any hoard is always rare and therefore of national importance but because of its size and detail this is particularly exciting.'

A spokesman for the British Museum confirmed that Darren's discovery was 'a significant Viking hoard'.

He said: 'Research on the hoard is ongoing and more information and images will be revealed at the time of the coroner's inquest in mid-December.'

A spokesperson for Carlisle's Tullie House Museum, where the hoard was originally taken, compared Mr Webster's find to that of the Cuerdale Hoard found on the southern bank of a bend of the River Ribble in 1840, the largest Viking silver hoard in north-western Europe.

05 November 2011

Magical Viking stone may be real

Our penchant to know how the medieval Vikings navigated the North Atlantic to Greenland and North America 500-years before Columbus was born continue with this article on the rediscovery of sunstone.
If you have an interest, click the links to my novels, where I refer to the stone's use, or sunstone for another good article on an old subject.
***
Telegraph UK

November 03, 2011

A Viking legend which tells of a glowing "sunstone" that, when held up to the sky, disclosed the position of the Sun on a cloudy day may have some basis in truth, scientists believe.


The ancient race is believed to have discovered North America hundreds of years before Christopher Columbus.

Now experiments have shown that a crystal, called an Iceland spar, could detect the sun with an accuracy within a degree allowing the legendary seafarers to navigate thousands of miles on cloudy days and during short Nordic nights.

Dr Guy Ropars, of the University of Rennes, and colleagues said "a precision of a few degrees could be reached" even when the sun was below the horizon.

An Iceland spar, which is transparent and made of calcite, was found in the wreck of an Elizabethan ship discovered thirty years ago off the coast of Alderney in the Channel Islands after it sank in 1592 just four years after the defeat of the Spanish Armada.

Viking legend tells of an enigmatic sunstone or s├│larsteinn that, when held up to the sky, revealed the position of the sun, even on overcast days or below the horizon, the study reveals.

One Icelandic saga describes how, during cloudy, snowy weather, King Olaf consulted Sigurd on the location of the Sun. To check Sigurd's answer, Olaf "grabbed a sunstone, looked at the sky and saw from where the light came, from which he guessed the position of the invisible Sun"

Using the polarisation of the skylight, as many animals like bees do, the Vikings could have used to give them true bearings.

The Viking routes in the North Atlantic were often subject to dense fog and the stone could also be used to locate the sun on very cloudy days.

The researchers said such sunstones could have helped the Vikings in their navigation from Norway to America before the discovery of the magnetic compass in Europe.

They would have relied upon the sun's piercing rays reflected through a piece of the calcite. The trick is that light coming from 90 degrees opposite the sun will be polarised so even when the sun is below the horizon it is possible to tell where it is.

They used the double refraction of calcite to pinpoint the sun by rotating the crystals until both sides of the double image are of equal intensity.

Navigation was based on tables showing the position of the sun in the sky at various times of year, prior to the use of the compass by Europeans, around the 12th century.

Added the researchers: "The Alderney discovery opens new possibilities as it looks very promising to find Iceland spars in other ancient shipwrecks, or in archaeological sites located on the seaside such as the Viking settlement with ship repair recently discovered in Ireland."

The study is published in the journal Proceedings of the Royal Society A.

04 November 2011

Linn Duchaill: Ireland's unlikely Viking capital

Twelve hundred years ago the medieval Vikings built their capitol city at the head of a bay in northeastern Ireland. The forgotten site has been found and excavation has begun.
***
Linn Duchaill: Ireland's unlikely Viking capital
By Conor Macauley BBC Newsline reporter


The Vikings chose Linn Duchaill as one of their first settlements in Ireland

A windswept barley field just south of Dundalk seems an unlikely spot for Ireland's capital. But if things had been different, Annagassan near Castlebellingham might have been the principal city on the island of Ireland.
Twelve hundred years ago it was the site of Linn Duchaill, one of the first Viking settlements, which rivalled Dublin in size and importance.
Folklore said it was there, but all traces of it had disappeared, until a group of archaeologists and local historians set out to prove its existence. Extensive field research and test digs have now done that.
What they found was a huge fortified settlement up to 150 acres in size, established by 841AD where the Vikings built and repaired their ships, traded and raided into the surrounding countryside.
Artist and historian Micheál McKeown was one of those who carried out extensive field research.

Raids

He said the Vikings sailed their ships about a mile upstream in the River Glyde, then built a heavily defended position by digging a long trench between the river and the Irish Sea, to completely cut themselves off. "Dublin developed more as a trading town, this appeared to be more of a raiding town," he said.
"From here they attacked inland, they flattened all the monasteries in County Louth, they went to Armagh three times in one year, they went as far as the Shannon, deep into Longford. So there had to be a great amount of Vikings here. I would estimate four or five thousand Vikings here with up to 200 ships."

Test trenches were dug at the site in August last year and a host of items were found. They included ships rivets, off-cuts of silver, which the Vikings used as currency, and a tiny weighing scale. Those are now on show at an exhibition in Dundalk's Louth County Museum, along with other items recovered years ago in the same area, including a slave chain, and an axe head - all of Viking vintage.


A slave chain is among the items found at the site

Around 70 people gathered there over the weekend for a two day conference to discuss the significance of the finds at the Annagassan site. Among them was Ned Kelly, the keeper of Irish antiquities at the National Museum of Ireland, one of those who helped uncover the settlement. "There's been a bit of a mystery about where exactly the site was located or what exactly the site consisted of, and antiquarians and historians and archaeologists have been trying to sort that mystery since about 1750. We've now absolutely confirmed the location and nature of the site. It's a very large site. It's one of the earliest sites, there's only one earlier site in Lough Neagh."

History

"Sites of this nature by virtue of the fact that the Vikings were an international phenomenon, are of international importance. This is a site that has the potential to tell us an awful lot about the early activities of the Vikings in Ireland. This is the phase prior to the establishment of towns like Dublin and Wexford. The site is well preserved, it's very big and the trial cuttings we put in last September show us that there's a great depth of archaeological deposits, so there's an enormous amount we can learn about early Viking settlement in Ireland."

Linn Duachaill was eventually abandoned in favour of Dublin. Experts believe that was because Dundalk Bay is shallow and access to the Glyde River was dependant on the tides, which effectively meant the Vikings were stranded upstream twice a day. That left them and their ships vulnerable to attack and it became too big of a risk.