Friday, 18 September 2009


Another hand-written addition to Barbeu-Dubourg’s timeline, which adds credence to the idea that the additions were written by the original author himself, is in 1752, ‘orages demontrés electrique’ - storms shown to be electrical.

In 1750, Benjamin Franklin had published a proposal for an experiment to prove that lightning was electricity by flying a kite in a storm, and such an experiment had been carried out by others in 1752. Franklin and Barbeu-Dubourg became friends and corresponded frequently. The correspondence can be seen here. Barbeu-Dubourg translated many of Franklin’s works into French (Aldridge 1951).

Franklin was also a friend of the other pioneer of the arithmetic timeline, Joseph Priestley. In Barbeu-Dubourg’s very first letter  to Franklin, he acknowledges receiving a copy of Priestley’s own timeline, and tactfully emphasises his own priority in invention while assuring Franklin that he won’t make an issue of it:
J’ai reçu avec reconnoissance et vu avec plaisir la carte biographique de M. Priestley qui est effectivement construite presque sur les memes principes que la mienne, sans plagiat de part ni d’autre, car je ne pretens point me prevaloir de la date.

I have received with gratitude and viewed with pleasure the biographical chart of Mr. Priestley which is in truth made on almost the same principles as my own, without plagiarism on either side, as I in no way claim primacy on account of the date. 

Aldridge, Alfred Owen. 1951. Jacques Barbeu-Dubourg, a French disciple of Benjamin Franklin. Proceedings of the American Philosophical Society. 95(4). 331-392.


In the copy of Barbeu-Dubourg’s Carte Chronographique held at Princeton, there are hand-written additions to the printed entries, four of them in the then recent past. Stephen Ferguson speculates that they were made by Barbeu-Dubourg himself (Ferguson 1991).

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).

Wednesday, 2 September 2009

Arithmetic scale - Blair's point of view

John Blair published a Chronology and History of the World, from the Creation to the Year of Christ 1753, which appeared in many subsequent editions and was widely used as a source, including by Priestley for his Chart of Biography of 1765.

Title page of Blair’s Chronology (1779 edition).
Collection of Stephen Boyd Davis. Photo: Stephen Boyd Davis

Blair praised Helvicus’ approach (see previous post), which used equal intervals of space for equal intervals of time, contrasting it with those whose ‘chief Aim seems to have been pointed, to the contracting History into a little Room as they could’. 
The Tables of Helvicus, which were publish’d in 1629, are what approach the nearest to the Plan of the present Work, and have been generally preferr’d by Men of Learning to all the rest; because they give a more united View of the Collateral Succession of different Kingdoms. Whereas the more Modern Tables of Talent, Marshal, Fresnoy, and those composed by an Anonymous Author from Petavius, have all of them made one great and fundamental Mistake. For their chief Aim seems to have been pointed, to the contracting History into a little Room as they could, by which they have lost the true Connection and Union of its Parts, which can never be preserved, without expanding them, according to the Series of single Years;  and we therefore venture to affirm, that this Principle is the most essential, in the Texture of a Chronological Table. For it is in Chronology as in Musick, where the Harmony does not arise, from any single Note, or from any Number of Notes, but from their properly proportioned and tuned to each other; where, without the exact Disposition of Time and Place, the true Union of Concert is broken, and the best Musick may become Discord.
Although Blair’s Chronology is a Table rather than a true Chronographic, his idea of the value of ‘a more united View of the Collateral Succession of different Kingdoms’ is important for future developments. It emphasises the idea of a visual whole in which the synchronisation of events may be directly seen.

Double page of Blair’s Chronology (1779 edition).
Collection of Stephen Boyd Davis. Photo: Stephen Boyd Davis

Detail of Blair’s Chronology (1779 edition).
The tables are engraved, rather than letterpress. Near the centre of this view is the death of Alexander Pope. 
Collection of Stephen Boyd Davis. Photo: Stephen Boyd Davis

Tuesday, 1 September 2009

Arithmetic scale for time

Making a list of historic events tends to produce a dense block of information with no wasted space between items. The focus is on the events, rather than on the time that they occupy. Periods with a lot of events take a lot of space, while those with few take less. This clearly has benefits in terms of economy of materials, and means that the user need not, for instance, turn a dozen almost empty pages in order to find an isolated incident. However this ‘packed array’ approach makes it difficult to see temporal patterns in the data, such as interesting alignments, gaps and clusters.

Here is a simple example of a time list which makes no use of empty space and simply puts one event after another: BBC timeline of Nepal

A slightly more sophisticated use of time-space is to have empty rows or columns for years (or other units of time) when nothing happened. This tends to also produce the result that each page or section represents the same amount of time. This approach goes back quite a long way.
Title page of Helwig [Helvicus], Christopher. 1687. The Historical and Chronological Theatre.
From the collection of Prof Michael Twyman. Photo: Stephen Boyd Davis.

In Helvicus’ Historical and Chronological Theatre, the case is made for spacing chronology in equal intervals. But Helvicus credits his predecessor, Scaliger, one of the most famous chronologers (about whom more another time) with introducing the practice. In the introductory note Of the equal Intervals of Centenaries and Denaries, i.e. Hundreds and Tens of Years he says:
What our Author (Scaliger) chiefly aim’d at, in his first contrivance of this Systeme, was a distribution of Years, from the beginning of the World down to our own times, into equal spaces or distances of Centenaries of Decads (viz. Hundreds and Tens of years) by reason of the singular use or advantage which therefrom result. For thus, the Reader cannot chuse but remember and declare, by the year of the World, or of Christ, wherein every Exploit or History happen’d, how many years the one was from the other; provided he make himself well acquainted with the Order and Continuation of the principal Governments of each Monarchy, by which guidance the Series of History will easily be retain’d in Memory. For every Page of his did contain one Hundred entire years; so it must on necessity fall out, that the correspondent Number of the next Page over against it should differ therefrom a Centenary of years. As for Example: the Peloponnesian War (which happened in the year of the World 3519) was placed in the end of the second Cell, (Area) or Denary: Opposite thereto, in the same part of the  following Page, was set down the Battel at Arbela, wherein Darius was subdued, and the Power was invested in Alexander; whence it appear’d, that there was the space of One Hundred years between the beginning of the Peloponnesian War, and the time wherein the Grecian Monarchy began.
So he is arguing that this design produces benefits in terms of:
  1. remembering sequences, including how long events lasted (the Order and Continuation of the principal Gorvernments); 
  2. the estimation of intervals between events.