| So we've been talking about different techniques of preserving artifacts. |
| Now I'd like to talk about an interesting case study |
| on the preservation of an artifact called the Palimpsest of Archimedes. |
| I'm sure you've heard of Archimedes, |
| one of the leading scientists in classical antiquity. |
| He lived more than 2,000 years ago in Greece. |
| He was regarded as one of the greatest mathematicians of history. |
| He figured out how to mathematically calculate the surface area and volume of a sphere, |
| and an accurate approximation of pi. |
| Unfortunately, not much of his work survived the passage of time. |
| He originally printed his findings on papyrus, |
| which was a processed and woven river reed fiber. |
| This material greatly decayed over time, |
| and his original scrolls were mostly lost. |
| What had survived had been brilliant. |
| Then, in 1906, a Palimpsest of Archimedes' writing was discovered. |
| Excuse me! Professor! |
| What is a Palimpsest? |
| Well, Parchment is made of animal skins that had been stretched tightly and dried. |
| Scholars used to take parchment that already had writing, |
| then wash it off with milk and write over the now-clean surface. |
| You have to understand that back then paper was uncommon for writing. |
| Instead, parchment was used for all the writing. |
| Okay! |
| Now, the interesting thing is that, |
| after the ink had been sitting on parchment for a long enough time, it soaks in. |
| And as the parchment aged, it dehydrated, making it lose much of its flexibility. |
| However, that extra drying time also made any captured inks within the skin rise to the surface. |
| So, seven hundred years later, |
| someone washed away a log of Archimedes' greatest work, |
| the letters and diagrams reappeared under the new letters. |
| It is now known as "The Archimedes Palimpsest", |
| and is probably by far the most important palimpsest anyone has found. |
| It contains the only known existing copy of Archimedes' finest work. |
| In it, he shows how mathematics can be applied to physical reasoning. |
| In 1906, the palimpsest was put on auction, |
| selling for 2 million dollars. |
| Luckily, it was not tucked away in a private collection. |
| The buyer agreed to have experts restore every single word Archimedes had written. |
| Now, his words can be shared with the world. |
| Unfortunately, we still have some problems with this Palimpsest. |
| Can anyone guess what they are? |
| Yes. Susan! |
| Well, it's been in storage for a long time, |
| probably not getting the proper care. |
| It's probably super crumbly, or moldy. |
| Exactly. |
| Some of it's moldy, some of it's been attacked by bugs. |
| The poor thing really went through the ringer. |
| On top of that, there is another problem with this Palimpsest. |
| Yes! John? |
| The letters on it aren't readable? |
| Essentially, yes. |
| Many archaeologists have used a variety of techniques such as Ultraviolet light |
| to try to make the letters more legible, but that didn't always work. |
| Fortunately, a physicist stepped forward - Bergman. |
| This guy was doing research on the iron within spinach leaves. |
| He proposed an idea that was very similar to how he was looking at iron in spinach. |
| He realized that the iron in the ancient ink would display |
| if exposed to a certain X-ray imaging method, |
| except for small portions of the text that couldn't be deciphered. |
| Now, with this technique, much of Archimedes' texts and drawings were revealed. |