Wednesday, 21 October 2009

Natural chronographics

Some natural processes produce a sort of chronographic display of their own – for example, the rings in sawn tree trunks represent the history of its growth, and geological strata represent the history of a landscape.

Tree rings can be crossdated to establish specific years in the tree’s history.
Image from Laboratory of Tree Ring Research at the University of Arizona.

Tree rings
As a page from the Laboratory of Tree Ring Research at the University of Arizona explains:
Many trees in temperate regions (those with a strong seasonal climate) produce annual growth layers that appear as rings in a cross sectional view of a tree stem. Variations in growing conditions from year-to-year produce a sequence of wide, narrow, and average ring widths. Over time the sequence forms a unique pattern that can be used like a fingerprint to determine the calendar year in which each ring was produced. [...]
Events in a tree’s life that have a recognizable impact on its growth may also be dated once the dates of the annual rings are known. Low to moderate intensity fires that burned through a forest may injure or scar surviving trees, leaving a clear record of their passage.
In at least one case the realisation that naturally occurring visual forms represent past time dawned during the same period as the early paper visualisations such as those of Barbeu-Dubourg and Priestley. This is the case with Hutton’s work on the formation of the earth.

Strata in rock caused by deposition over centuries.
Lake Bolsena, Italy. Photo: Stephen Boyd Davis.

James Hutton (1726-1797) sought to explain rock formations. His Theory of the Earth; or an Investigation of the Laws observable in the Composition, Dissolution, and Restoration of Land upon the Globe and Concerning the System of the Earth, its Duration and Stability put forward the idea that the layers to be seen where rock is exposed represent ancient depositions such as occur under water, and that places where the layers are uptilted or broken record violent subsequent upheavals.

An ironic outcome of the work in geology was to move the goalposts – at least at one end of the pitch. The beginning of time moved away to an almost ungraspable distance rather than the relatively comfortable proximity of, say, 4004BC calculated by Archbishop Ussher. The many universal chronologies and chronographies which contained all history from the beginning of all things to the present day within roughly 6000 years would become increasingly out of step with the realisation of the real extent of the past.

Event-based and time-based
These natural chronographics record time unequally: sedimentary deposit during one century may produce a thick layer of rock while that of another century ends up as only a narrow band. A year of strong growth produces a broad tree ring while one of poor growth makes a narrow one. These are effectively event-based representations. A time-based representation, on the other hand, uses what we might call Newtonian time – a regular, uniform, clock-like scale, in which events appear. 

Further reading on the Web:

Monday, 5 October 2009

More on Helvicus and the arithmetic scale for time

On 1 September I noted that, while trumpeting the advantages of using equal space to represent equal time, Helvicus credited his predecessor, the renowned chronologer Scaliger, with inventing the idea.

But I was wrong.

Fooled by the translation in an English edition of 1687, I spent half a day in the British Library on a wild goose chase. I was looking at five works by Scaliger - the De Emendatione Temporum of 1583, 1598 and 1629 and the Thesaurus Temporum of 1606 and 1658 - without being able to find any of evidence of this arithmetic scale for time. I was hampered by having almost no Latin and no Greek, but still expected to identify this key aspect of the layout. I managed to find the Peloponnesian War at DCCCCXLVI (on p99) in Eusebius Chronicorum Liber Posterior within the Thesaurus Temporum but the corresponding part of the next page certainly did not contain the item of 100 years later as Helvicus had seemed to describe. Like most chronologies, Scaliger’s simply uses as much space as he needs to record and describe each event, not allocating equal space to equal time at all.

A part of the page in the English translation of Helvicus which appears to say that Scaliger preceded Helvicus in using equal space for equal time in laying out his chronologies. 
Helwig [Helvicus], Christopher. 1687. The Historical and Chronological Theatre.
From the collection of Prof Michael Twyman. Photo: Stephen Boyd Davis.

But it seems the problem is in the translation! Apparently in the first edition of his work, in Latin, in 1609, Helvicus definitely claims the credit for himself: ‘the main goal I aimed at in this treatment is an equal distribution of years between the creation and our time in intervals of 100 and 10 years, because that is so useful’ (Praecipuum, quod in hoc Systemate spectavi, est annorum a Mundo condito ad nostra tempora usque per aequalia Centenariorum et Decadum spacia distributio, ob eximium usum, qui inde resultat). The translator seems to have thought that Helvicus was crediting Scaliger and inserted the name himself – hence his use of brackets around Scaliger’s name indicating that the name as such was not in the original. My thanks to Prof. Anthony Grafton of Princeton University for unravelling this for me.

Incidentally Prof. Grafton has an important book coming out in this area next year. More on this later.