The discovery of Herculaneum added by hand to the Carte Chronographique of Barbeu-Dubourg at Princeton. Image: Rare Book Division, Department of Rare Books and Special Collections, Princeton University Library.
Some of them represent the emergence of significant new knowledge. The one I want to highlight here is the added entry for 1747: ‘ville de Herculane trouvée sous terre’ - the town of Herculaneum discovered underground. Herculaneum had been buried by volcanic deposits, along with Pompeii, Stabiae and Oplontis, in the eruption of Mount Vesuvius in 79 AD. Just to read the addition in its hand-written form produces a frisson of presence, sharing the excitement they must have felt when it was rediscovered. By lucky chance I was able to visit Herculaneum just a few days after being in Princeton.
Herculaneum in 2009. The full height of buildings was encased by lava flows within hours and preserved until the 18th Century when excavation began to both reveal and destroy the remains. Photo: Stephen Boyd Davis.
Herculaneum and sites like it are special in relation to chronology and chronographics because they do not have an obvious natural visual chronology, making them quite unlike normal archaeological excavations. Normally a dig will cut down progressively through quite thin layers of material, each representing the crushed debris of a quite extended period. See Harris’ Laws of Archaeological Stratigraphy in the Wikipedia article on the Harris Matrix. A vertically cut cross-section will therefore show layers or bands in a kind of natural chronographic representing hundreds or thousands of years. But at Herculaneum the deposits many metres thick represent not years but days or even hours. The pyroclastic flow from Vesuvius swamped the town, even filling internal spaces within buildings so preventing them collapsing as more and more material fell from above. Digging up the town therefore reveals an archaeological snapshot rather than the usual extended duration.
Foreground, a well-preserved building at Herculaneum. Background, part of the excavation wall showing the solid mass of tufa deposited in hours through pyroclastic flow. Normally such depth present a succession of visual layers representing deposition over centuries. Photo: Stephen Boyd Davis.
Ferguson, Stephen. 1991. The 1753 Carte chronographique of Jacques Barbeu-Dubourg. Princeton University Library Chronicle (Winter 1991).