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An Illustrated History of the Gas Mask

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You probably knew that gas masks were pretty common back in WWII, but did you know their use dates back all the way to ancient Greece? It's true: All the way back in antiquity, the common sponge was used as a gas mask as necessary. Workers in dangerous fields have used gas masks since 850 A.D. when the Banu Musa brothers of Iraq designed an early prototype meant to protect workers working in polluted wells. Gas masks for breathing in smoke-filled areas have been around since at least 1820. You can learn more about the history of this life-saving device in this fascinating article on i09 that is also accompanied with pictures of historical gas masks. While these ancient gas masks were almost certainly less effective than the ones we use these days, they do show that as long as there have been dangerous gasses around, humans have worked to filter out the dangers so we could breathe easily.
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Stones, Bones, and Wrecks
8 New Ancient Ships Found at the 'Shipwreck Capital of the World'
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The number of wrecks discovered at the "shipwreck capital of the world" continues to grow. According to Haaretz, the latest find adds eight new wreck discoveries, bringing the total up to 53 sunken ships in a 17-mile stretch off the coast of Fourni, Greece.

As Mental Floss reported, in 2015 archaeologists working off the coast of Fourni identified 22 shipwrecks dating back to 700 BCE—already an historic find. But additional dives conducted by the Hellenic Ministry of Culture and the RPM Nautical Foundation have continued to yield new discoveries. Nine months later, in June 2016, the Fourni Underwater survey turned up 23 more ancient, Medieval, and post-Medieval shipwrecks in the area with the help of local fishermen and sponge divers. The latest expedition took place in June 2017.

Divers inspect and survey an ancient amphora near the shipwreck site.

The Fourni archipelago, consisting of 13 tiny islands, never hosted a sizable town, but it was an important stopping point for shipping routes between the Black Sea, the Aegean Sea, and on to Cyprus, the Levant, and Egypt. The area may have been a hotspot for ships seeking safe harbor from violent storms in that part of the Aegean Sea, as Peter Campbell of the RPM Nautical Foundation told Haaretz. It wasn’t an entirely safe destination for merchant ships, though; it was also a pirate haven.

Some of the latest wrecks found include a ship from the Greek Classical Period—around 500 BCE to 320 BCE—carrying Greek amphorae (ceramic jars), a Roman ship with origins in the Iberian Peninsula, and anchors dating back to the Archaic Period (800 to 479 BCE). Researchers found more stone, lead, and iron anchors all the way up to the Byzantine Empire, which lasted until the 15th century.

Two conservationists sit at a table working with shards of ancient pottery.

The ancient trade routes that crisscrossed the Mediterranean (and the dangers of ancient seafaring) have made the area a fertile ground for millennia-old shipwrecks even outside of Fourni. As recently as 2016, divers off the coast of Israel stumbled upon a 1600-year-old merchant ship filled with Roman artifacts. In 2015, Italian divers discovered the wreck of a 2000-year-old ship carrying terra cotta tiles in deep waters near Sardinia.

The Fourni project is still ongoing, and researchers plan to conduct a fourth season of underwater surveying in 2018. Once the project completes a full survey and documentation of the area, the researchers may consider excavating some of the wrecks.

[h/t Haaretz]

All photos by Vasilis Mentogianis courtesy the RPM Nautical Foundation

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J. P. Oleson
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science
Time Has Only Strengthened These Ancient Roman Walls
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J. P. Oleson

Any seaside structure will erode and eventually crumble into the water below. That’s how things work. Or at least that’s how they usually work. Scientists say the ancient Romans figured out a way to build seawalls that actually got tougher over time. They published their findings in the journal American Mineralogist.

The walls’ astonishing durability is not, itself, news. In the 1st century CE, Pliny the Elder described the phenomenon in his Naturalis Historia, writing that the swell-battered concrete walls became "a single stone mass, impregnable to the waves and every day stronger."

We know that Roman concrete involved a mixture of volcanic ash, lime, seawater, and chunks of volcanic rock—and that combining these ingredients produces a pozzolanic chemical reaction that makes the concrete stronger. But modern cement involves a similar reaction, and our seawalls fall apart like anything else beneath the ocean's corrosive battering ram.

Something else was clearly going on.

To find out what it was, geologists examined samples from walls built between 55 BCE and 115 CE. They used high-powered microscopes and X-ray scanners to peer into the concrete's basic structure, and a technique called raman spectroscopy to identify its ingredients.

Microscope image of crystals in ancient Roman concrete.
Courtesy of Marie Jackson

Their results showed that the pozzolanic reaction during the walls' creation was just one stage of the concrete toughening process. The real magic happened once the walls were built, as they sat soaking in the sea. The saltwater did indeed corrode elements of the concrete—but in doing so, it made room for new crystals to grow, creating even stronger bonds.

"We're looking at a system that's contrary to everything one would not want in cement-based concrete," lead author Marie Jackson, of the University of Utah, said in a statement. It's one "that thrives in open chemical exchange with seawater."

The goal now, Jackson says, is to reproduce the precise recipe and toughen our own building materials. But that might be harder than it sounds.

"Romans were fortunate in the type of rock they had to work with," she says. "They observed that volcanic ash grew cements to produce the tuff. We don't have those rocks in a lot of the world, so there would have to be substitutions made."

We still have a lot to learn from the ancient walls and their long-gone architects. Jackson and her colleagues will continue to pore through Roman texts and the concrete itself, looking for clues to its extraordinary strength.

"The Romans were concerned with this," Jackson says. "If we're going to build in the sea, we should be concerned with it too."

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