Herculaneum papyri
The Herculaneum papyri are more than 1,800 papyrus scrolls discovered in the 18th century in the Villa of the Papyri in Herculaneum. They had been carbonized when the villa was engulfed by the eruption of Mount Vesuvius in 79 AD. The papyri, containing a number of Greek philosophical texts, come from the only surviving library from antiquity that exists in its entirety. However, reading the scrolls is extremely difficult, and can risk destroying them. The evolution of techniques to do this continues. The majority of classical texts referred to by other classical authors are lost, and there is hope that the continuing work on the library scrolls will discover some of these. For example, as many as 44 works discovered were written by the 1st-century BC Epicurean philosopher and poet Philodemus, a resident of Herculaneum, who possibly formed the library, or whose library was incorporated in it. Discovery

Due to the eruption of Mount Vesuvius in 79 AD, bundles of scrolls were carbonized by the intense heat of the pyroclastic flows. This intense parching took place over an extremely short period of time, in a room deprived of oxygen, resulting in the scrolls' carbonization into compact and highly fragile blocks. They were then preserved by the layers of cement-like rock. In 1752, workmen of the Bourbon royal family accidentally discovered what is now known as the Villa of the Papyri. There may still be a lower section of the Villa's collection that remains buried. Ethel Ross Barker noted in her 1908 Buried Herculaneum:

Excavations

In the 18th century, the first digs began. The excavation appeared closer to mining projects, as mineshafts were dug, and horizontal subterranean galleries were installed. Workers would place objects in baskets and send them back up. With the backing of Charles III of Spain (1716 – 1788), Roque Joaquín de Alcubierre headed the systematic excavation of Herculaneum with Karl Jakob Weber. Barker noted in her 1908 Buried Herculaneum, "By the orders of Francis I land was purchased, and in 1828 excavations were begun in two parts  apart, under the direction of the architect. Carlo Bonucci. In the year 1868 still further purchases of land were made, and excavations were carried on in an eastward direction till 1875. The total area now open measures 300 by 150 perches (1510 by 756 meters). The limits of the excavations to the north and east respectively are the modern streets of Vico di Mare and Vico Ferrara. It is here only that any portion of ancient Herculaneum may be seen in the open day." It is uncertain how many papyri were originally found as many of the scrolls were destroyed by workmen or when scholars extracted them from the volcanic tuff. The official list amounts to 1,814 rolls and fragments, of which 1,756 had been discovered by 1855. In the 90s it was reported that the inventory now comprises 1,826 papyri, with more than 340 are almost complete, about 970 are partly decayed and partly decipherable, and more than 500 are merely charred fragments. In a 2016 open letter, academics asked the Italian authorities to consider new excavations, since it is assumed that many more papyri may be buried at the site. Authors argue that "the volcano may erupt again and put the villa effectively beyond reach" and "Posterity will not forgive us if we squander this chance. The excavation must proceed". Post-excavation history
In 1802, King Ferdinand IV of Naples offered six rolls to Napoleon Bonaparte in a diplomatic move. In 1803, along with other treasures, the scrolls were transported by Francesco Carelli. Upon receiving the gift, Bonaparte then gave the scrolls to Institut de France under charge of Gaspard Monge and Vivant Denon. In 1810, eighteen unrolled papyri were given to George IV, four of which he presented to the Bodleian Library; the rest are now mainly in the British Library. Unrolling

Since their discovery, previous attempts used rose water, liquid mercury, vegetable gas, sulfuric compounds, papyrus juice, or a mixture of ethanol, glycerin, and warm water, in hopes to make scrolls readable. According to Antonio de Simone and Richard Janko at first the papyri were mistaken for carbonized tree branches, some perhaps were even thrown away or burnt to make heat. Opening a scroll would often damage or destroy the scroll completely. If a scroll had been successfully opened, the original inkexposed to airwould begin to fade. In addition, this form of unrolling often would leave pages stuck together, omitting or destroying additional information. With X-ray micro-computed tomography (micro-CT), no ink can be seen, as carbon-based ink is not visible on carbonized papyrus. Physical unrolling

Early attempts

Following the discovery of the Herculaneum papyri in 1752, per the advice from Bernardo Tanucci, King Charles VII of Naples established a commission to study them. Possibly the first attempts to read the scrolls were done by the artist Camillo Paderni who was in charge of recovered items. Paderni used the method of slicing scrolls in half, copying readable text, by removing papyri layers. This transcription procedure was used for hundreds of scrolls, and in the process destroyed them. In 1756, Abbot Piaggio, conserver of ancient manuscripts in the Vatican Library, used a machine he also invented, to unroll the first scroll, which took four years (millimeters per day). The results were then swiftly copied (since the writing rapidly disappeared: see below), reviewed by Hellenist academics, and then corrected once more, if necessary, by the unrolling/copying team. In 1802, King Ferdinand IV of Naples appointed Rev. John Hayter to assist the process. From 1802 to 1806, Hayter unrolled and partly deciphered some 200 papyri. These copies are held in the Bodleian Library, where they are known as the "Oxford Facsimiles of the Herculaneum Papyri". In January 1816, Pierre-Claude Molard and Raoul Rochette led an attempt to unroll one papyrus with a replica of Abbot Piaggio's machine. However, the entire scroll was destroyed without any information being obtained. From 1819 until 1820, Humphry Davy was commissioned by the prince regent George IV to work on the Herculaneum papyri. Although it is considered that he had only limited success, Davy's chemical method, which used chlorine, managed to partially unroll 23 manuscripts. In 1877, a papyrus was taken to a laboratory in the Louvre. An attempt to unravel it was made with a "small mill", but it was unsuccessful and was partially destroyed, leaving only a quarter intact. By the middle of the 20th century, only 585 rolls or fragments had been completely unrolled, and 209 unrolled in part. Of the unrolled papyri, about 200 had been deciphered and published, and about 150 only deciphered. Modern attempts

The bulk of the preserved manuscripts are housed in the Office of Herculaneum papyri in National Library of Naples. In 1969, Marcello Gigante founded the creation of the International Center for the Study of the Herculaneum Papyri (Centro Internazionale per lo Studio dei Papiri Ercolanesi; CISPE). With the intention of working toward the resumption of the excavation of the Villa of the Papyri, and promoting the renewal of studies of the Herculaneum texts, the institution began a new method of unrolling. Using the 'Oslo' peeling method, the CISPE team separated individual layers of the papyri. One of the scrolls exploded into 300 parts, and another did similarly but to a lesser extent. Since 1999, the unrolled papyri have been digitized at the Brigham Young University by applying multi-spectral imaging (MSI). International experts and prominent scholars participated in the project. On 4 June 2011 it was announced the task of digitizing 1,600 Herculaneum papyri had been completed. MSI helps spot ink because the ink and the charred papyrus has different reflectivities in the 950 nm infrared band. The images are not actually "multispectral", but only consists of data in this 950-nm band. In 2019, a multinational European team reported that SWIR HSI (shortwave-infrared hyperspectral imaging), which combines several bands in the 1000-2500 nm range, detects ink on unrolled papyri better than the 950 nm technique does. Virtual unrolling 
Several research groups proposed to unroll the scrolls virtually, using X-ray phase-contrast tomography (XPCT, "phase-contrast CT"), possibly with a synchrotron light source. Proposed method has three steps: volumetric scanning, segmentation, layered texture generation and restoration. Since 2007, a team working with Institut de Papyrologie and a group of scientists from Kentucky have been using x-rays and nuclear magnetic resonance to analyze the artifacts. In 2009, the Institut de France in conjunction with the French National Center for Scientific Research imaged two intact Herculaneum papyri using X-ray micro-computed tomography (micro-CT) to reveal the interior structures of the scrolls. The team heading the project estimated that if the scrolls were fully unwound they would be between  long. The internal structure of the rolls was revealed to be extremely compact and convoluted, defeating the automatic unwrapping computer algorithms which the team had developed. Unfortunately, no ink could be seen on the small samples imaged, because carbon-based inks are not visible on the carbonized scrolls. However, some scrolls were written with ink containing lead. In September 2016, Brent Seales, a computer scientist at the University of Kentucky, successfully used virtual unrolling to read the text of a charred parchment from Israel, the En-Gedi Scroll. Process 
The virtual unwrapping process begins with using a volumetric scan to scan the damaged scroll. These scans are non-invasive, and generate a 3D mapping which differentiates between the ink and the paper. The virtual unwrapping process is independent of which type of volumetric scan is used, which allows scientists to test out different scanning methods to find which distinguishes ink from paper best and which easily accommodates scanning upgrades. The only data needed for the virtual unwrapping process is this volumetric scan, so after this point the scroll is safely returned to the archive. In the case of the Herculaneum papyri, the volumetric scan used phase-contrast CT. This method of volumetric scanning was chosen because Herculaneum papyri have carbon-based ink, which will have the same material characteristics as the carbon-based papyrus. This makes it difficult to image using many of the traditional imaging techniques, which often use differences in the light absorption/emission characteristics of different materials to create these volumetric scans. XPCT, on the other hand, examines the phase of x-ray radiation after it emerges from the scroll to determine its composition. Because the ink is raised relative to the papyrus, the radiation will be traveling in the material of the scroll slightly longer when it passes through a spot with ink than when it passes through a spot with a blank space. This means that when the radiation emerges from the paper, its phase will be slightly different than that of the empty space, allowing researchers to distinguish ink-covered spots from blank spots. While this technique does allow researchers to visualize places with ink, it is much less clear than techniques such as CT scans which distinguish between different materials because slight changes (thinner ink, thicker papyrus, folds in the papyrus) all contribute to noise in the volumetric scan. The volumetric scan is used to associate the composition of the scroll with corresponding positions, called voxels or volume-pixels. The goal of the virtual unwrapping process is to determine the layered structure of the scroll and try to peel back each layer while keeping track of which voxel. By transforming the voxels from a 3D volumetric scan to a 2D image, the writing on this inside can be revealed. This process happens in three steps: segmentation, texturing and flattening. The first stage of the virtual unwrapping process, segmentation, involves identifying geometric models for the structures within the virtual scan of the scroll. Because of the extensive damage, the parchment has become deformed and no longer has a clearly cylindrical geometry. Instead, some portions may look planar, some conical, some triangular, etc. Therefore, the most efficient way to assign a geometry to the layer is to do so in a piecewise fashion. Rather than modeling the complex geometry of the entire layer of the scroll, the piecewise model breaks each layer into more regular shapes that are easy to work with. This makes it easy to virtually lift off each piece of the layer one at a time. Because each voxel is ordered, peeling off each layer will preserve the continuity of the scroll structure. The second stage, texturing, focuses on identifying intensity values that correspond with each voxel using texture mapping. From the volumetric scan, each voxel has a corresponding composition. After virtually peeling off the layers during the segmentation process, the texturing step matches the voxels of each geometric piece to their corresponding compositions so that an observer is able to see the text written on each piece. In ideal cases, the scanned volume will match perfectly with the surface of each geometric piece and yield perfectly rendered text, but there are often small errors in the segmentation process that generate noise in the texturing process. Because of this, the texturing process usually includes nearest-neighbor interpolation texture filtering to reduce the noise and sharpen the lettering. After segmentation and texturing, each piece of the virtually deconstructed scroll is ordered and has its corresponding text visualized on its surface. This is, in practice, enough to 'read' the inside of the scroll, but it is often best to convert this to a 2D flat image to demonstrate what the scroll's parchment would have looked like if they could physically unravel without damage. This requires the virtual unwrapping process to include a step that converts the curved 3D geometric pieces into flat 2D planes. After segmenting, textualizing, and flattening the scroll to obtain 2D text fragments, the last step is a merge step meant to reconcile each individual segment to visualize the unwrapped parchment as a whole. This involves two parts: texture merging and mesh merging. Texture merging aligns the textures from each segment to create a composite. This process gives feedback on the quality of the segmentation and alignment of each piece. Mesh merging is more precise and is the final step in visualizing the unwrapped scroll. This type of merging recombines each point on the surface of each segment with the corresponding point on its neighbor segment to remove the distortions due to individual flattening. This step also re-flattens and re-textures the image to create the final visualization of the unwrapped scroll. These techniques, while successful at isolating the layers of the papyri, had difficulty detecting text clearly due to the complex geometry of the sheets, such as the criss-cross structure of the papyrus fibres and the sheets, pleats, holes, tears, and contamination from the extensive damage. One potential source of error might be the 3D volumetric scan itself or the flattening procedure used to read it since the algorithms are not able to perfectly prevent distortions in the reading of these papyri. Seales presented in 2018 readability of parts of a Herculaneum papyri (P.Herc. 118) from the Bodleian Libraries, at Oxford University, which was given by the King Ferdinand of Naples to the Prince of Wales in 1810. The imaging method Seales used involved a hand-held 3-D scanner called an Artec Space Spider. The same year he demonstrated readability success of another Herculaneum scroll, with help of the particle accelerator Diamond Light Source, through a powerful x-rays imaging technique, letter ink which contains trace amounts of lead were detected. Prior to this he demonstrated successful virtual unrolling without detecting ink on Herculaneum scrolls. Vesuvius Challenge 
In 2023, Nat Friedman, Daniel Gross, and computer scientist Brent Seales announced the Vesuvius Challenge, a competition to "decipher Herculaneum scrolls using 3D X-ray software." The Vesuvius Challenge will award a $700,000 grand prize to the first team that can extract four passages of text from two intact scrolls using 3D X-ray scans. On 12 October 2023, the project awarded $40,000 to Luke Farritor, a 21-year-old computer student at the University of Nebraska, for successfully detecting the first word in an unopened scroll: porphyras (). With this milestone "first word" award included, the project has awarded $260,000 in total for segmentation tooling and ink detection (from segmented volumes). Significance

Until the middle of the 18th century, the only papyri known were a few survivals from medieval times. Most likely, these rolls would never have survived the Mediterranean climate and would have crumbled or been lost. Indeed, all these rolls have come from the only surviving library from antiquity that exists in its entirety. These papyri contain a large number of Greek philosophical texts. Large parts of Books XIV, XV, XXV, and XXVIII of the magnum opus of Epicurus, On Nature and works by early followers of Epicurus are also represented among the papyri. Of the rolls, 44 have been identified as the work of Philodemus of Gadara, an Epicurean philosopher and poet. The manuscript "PHerc.Paris.2" contains part of Philodemus' On Vices and Virtues. The Stoic philosopher Chrysippus is attested to have written over 700 works, all of them lost, with the exception of a few fragments quoted by other authors. Segments of his works On Providence and Logical Questions were found among the papyri; a third work of his may have been recovered from the charred rolls. Parts of a poem on the Battle of Actium have also survived in the library. In May 2018, it was reported that fragments of the lost work Histories by Seneca the Elder have been found on a papyrus scroll (PHerc. 1067). Gallery

See also

Conservation issues of Pompeii and Herculaneum
Friends of Herculaneum Society
Ancient Greek literature
Ercolano
Oxyrhynchus Papyri
Afghan Geniza, collection of Jewish papyri fragments found in Afghanistan
Cairo Geniza, similar cache of ancient religious and secular documents
Dunhuang manuscripts, similar cache of ancient religious and secular documents
Elephantine papyri and ostraca, similar cache of ancient religious and secular documents
Timbuktu manuscripts

References

Further reading
 Armstrong, David. 2011. "Epicurean Virtues, Epicurean Friendship: Cicero vs. The Herculaneum Papyri." In Epicurus and the Epicurean Tradition. Edited by Jeffrey Fish and Kirk R. Sanders. Cambridge; New York: Cambridge University Press
 
 
 Houston, George W. 2013. "The Non-Philodemus Book Collection in the Villa of the Papyri." In Ancient Libraries Edited by  Jason König, Katerina Oikonomopoulou, Greg Woolf, 183-208. Cambridge; New York : Cambridge University Press. Janko, Richard. 1993. Philodemus Resartus: Progress in Reconstructing the Philosophical Papyri from Herculaneum. In Proceedings of the Boston Area Colloquium in Ancient Philosophy: VII, 1991. Edited by John J. Cleary. Lanham, Md. & London: University Press of America. Seales, W. Brent, Jim Griffioen, and David Jacobs. 2011. "Virtual Conservation: Experience with Micro-CT and Manuscripts." In Eikonopoiia: Digital Imaging of Ancient Textual Heritage: Proceedings of the International Conference, Helsinki, 28–29 November 2010. Edited by Vesa Vahtikari, Mika Hakkarainen, and Antti Nurminen, 81–88. Helsinki: Societas Scientiarum Fennica. Sider, David. 2005. The Library of the Villa dei Papiri at Herculaneum. Los Angeles: J. Paul Getty Museum
 Zarmakoupi, Mantha, ed. 2010. The Villa of the Papyri at Herculaneum: Archaeology, Reception, and Digital Reconstruction. Berlin: de Gruyter. Vassallo, Christian. 2021. The Presocratics at Herculaneum: A Study of Early Greek Philosophy in the Epicurean Tradition. Berlin - Boston: de Gruyter. Turenko, Vitalii. 2022. New edition of Рresocratic fragments: materials of Herculaneum papyri. Sententiae, 41(2), 166–176. External links
 Out of the Ashes: Recovering the Lost Library of Herculaneum – documentary film distributed by Brigham Young University
 Würzburg Center for Epicurean Studies
 Porter, James I., Hearing Voices: The Herculaneum Papyri and Classical Scholarship
 UCLA Department of Classics: The Philodemus Project, Archived at the Wayback Machine on 25 August 2011. The Friends of Herculaneum Society
 An incomplete list of papyri from Herculaneum with high resolution photographs . A Guide to Editions and Translations of the Principal Works Discovered at Herculaneum and Related Texts
 The Digital Restoration Initiative at the University of Kentucky

Papyrology
1st-century manuscripts
Herculaneum
Archaeological discoveries in Italy
Papyrus collections