She was first raised from her underwater resting place more than 30 years ago and has been prized as an archaeological gem, but it appears the Mary Rose still has some secrets to surrender.
A Mary Rose cannon ball showing a hole in the lead coating where the iron inclusion has oxidised and left a hollow in the centre of the cannon ball
Scientists studying Henry VIII’s naval flagship, which sank 468 years ago off the south coast of England in a battle with the French, are making new discoveries about the vessel that will change our understanding of history.
New finds will be among 19,000 artefacts going on show in a new £23 million museum, built around the skeleton of the vessel, due to open later this year.
A 3D neutron tomograph of a 1kg lead cannon ball. The cubic iron inclusion is clearly visible within the lead sphere
Archaeologists have found the remains of a dog that lived on board, and longbows found on board have revealed a great deal about archery at the time.
Among the items most exciting archaeologists are cannonballs believed to be early examples of armour-piercing rounds.
Such shells were thought to have been developed during the late 1800s, before the technology was refined during the world wars.
But the new findings by experts working with the Mary Rose Trust, which has been preserving the ship, now suggest the technology was being used several centuries earlier — although it could also have been a money-saving strategy, using cheaper iron inside the lead balls.
Powerful imaging technology has revealed cubic-shaped lumps of iron encased in the soft, lead cannonballs, which would have allowed guns to punch through the sides of enemy vessels.
Main deck guns
The cannonballs would have worked much like a modern-day armour-piercing round — the soft outer material, in this case lead, would have deformed on impact, throwing the hard iron core through the armour plating.
The trust hopes to conduct tests at the The Royal Armouries to try to better understand the damage they would have inflicted.
Alex Hildred, of the archaeology team, said: “We first noticed something strange when the lead cannonballs began to rust. Some burst open so that rust came almost pouring out of where it had split.
“We found there were small iron cores inside. This could have been done to make the cannonballs cheaper or it may have made it easier to make while at sea if you had an iron core — you had to carry less of the heavier lead.
“But they would probably have worked like a soft-nose bullet. They could be some of the earliest examples of armour-piercing projectiles.”
Professor Sue Kilcoyne (left) and PhD student Amanda Wynne looking at the X ray of a cannonball at the Paul Scherrer Institute
Professor Susan Kilcoyne, a physicist at the University of Huddersfield, discovered the iron cores using high powered equipment that fired neutrons at the cannonballs, allowing her to see through the lead, which is impenetrable to X-rays.
She now hopes to use similar techniques to examine whether the iron inside the cannonballs has been cast or was worked by blacksmiths to harden it.
This should help to reveal whether the iron was used purely to lower costs or had deliberately hardened to increase the amount of damage that could be inflicted.
The findings are the latest in a string of important scientific discoveries about the Mary Rose since it was raised from the mud at the bottom of The Solent near the Isle of White 30 years ago.
The 150 foot vessel capsized and sank in 1545 during a battle with a French invasion fleet, killing 500 sailors on board.
It spent the centuries on the sea bed under 45 feet of water, where layers of silt helped to preserve the vessel before it was salvaged in October 1982.
Conservation experts and archaeologists have since been fighting to save the salt laden timbers from attack by acid producing bacteria, and so have been slowly preserving the ship by spraying her fresh water and a waxy resin.
Musical instruments have also been found among the wreck and experts have discovered that gold coins on board had been debased in a bid to make them cheaper to produce.
Many of the artefacts found to have been on board the Mary Rose when it was raised, however, are also suffering from having spent centuries emersed in sea water.
The salt has leached into many of the bronze and iron guns, while arrow heads, lead shot and cannonballs all have to be carefully stored in climate controlled rooms to ensure they do not corrode.
A new £23 million museum has been built around the Mary Rose at Portsmouth Dockyard
Scientists are developing new techniques they hope will allow them to preserve the treasures.
They are using high-powered X-rays to study how the corrosion is taking place and have developed a new coating to protect the metals from further damage.
Professor Mark Dowsett, from the department of physics at Warwick University, used X-ray Magnetic Scattering Instrument in Grenoble, which received £6 million of funding from the UK Government last year, to analyse the microscopic changes that have occurred in the guns, cannonballs and chain mail recovered from the Mary Rose as they have been exposed to air.
He said: “The Tudor armour piercing canon balls are lead with a small piece of unpleasantly shaped iron inside. This mixture of materials is almost fatal as the seawater attacks the iron and causes it to swell to two or three times its size, cracking the lead and allowing air inside making the problem worse.
“There are a vast range of metals they have recovered that ranges from tiny pieces of silver wire from chain mail and copper shoe lace tips and iron guns and brass canons.
“It presents an enormous difficulty as each metal will corrode differently. We are developing a protective coating, which we hope will be useful for the lead munitions for the Mary Rose.”
A new £23 million museum has been built around the ship at Portsmouth Dockyard. It is due to open to the public for the first time at the end of May.
The wooden wreck will be displayed alongside 19,000 artefacts, including many of the giant bronze guns that bristled from the vessel.
John Lippiett, chief executive of the Mary Rose Trust, said: “We found tens of thousands of artefacts on board and they have been more than 30 years in excavation.
“What is clear is that even as the new museum opens later this year, there is still a lot of secrets the Mary Rose has to reveal.”
Telegraph Travel offers the The Mary Rose and Portsmouth's Maritime History tour, operated by Travel Editions, from £299pp for three days. Offer includes two talks by Christopher Dobbs, Head of Interpretation for the Mary Rose Trust, who worked as a diver on the excavation and recover of Mary Rose and a private viewing of the extensive and fascinating artefacts at the new Mary Rose Museum. Call 08448730323 or visit www.telegraph.co.uk/maryrose