One of the world’s most significant archaeological discoveries of a scientific instrument is to be sold by Bonhams on 21 March 2007 in Knightsbridge, London.
The incredibly rare 700 year-old quadrant was the pocket calculator of the 14th century and a lot more besides.
A Canterbury Tale…
In 2005, during excavations for the extension of a fusion restaurant in Canterbury, an unusual discovery was made. A scientific instrument known in the middle ages as the ‘quadrans novus’ – today, often labelled as the ‘astrolabe quadrant’ - was found on a site known as the ‘House of Agnes’, a 17th century inn on the main road to London, just beyond the Westgate of the city. There it lay beneath a series of clay floors, inside a sealed soil deposit dated to circa 1375-1425.
Now, two years on, the astrolabe quadrant – used for telling the time and making astrological and mathematical calculations, such as, measuring the height of buildings and trees or the depth of a well – has been dated to circa 1388 – one year after Geoffrey Chaucer started to write The Canterbury Tales. Chaucer was familiar with the function of a quadrant, writing a ‘Treatise on the Astrolabe’ in 1391.
This quadrant is one of only eight examples known in the world. It was made in England and is one of the oldest and smallest in existence.
Ellie Dekker, a leading scholar on the subject of astrolabe quadrants, comments: “Finding a complete scientific instrument during archaeological work is very rare, but finding an instrument that was used only by scholars well versed in the secrets of the sky is exciting.”
Jon Baddeley, Bonhams’ director of scientific instruments, adds: “This is an extraordinary object, which would have been owned by an educated clerical scholar. He would have needed a good understanding of the rudiments of astronomy and of mathematics, so the owner must be counted among the small circle of scientifically educated scholars in 14th century England. The small pocket-sized instrument suggests it was used by a traveller.”
The brass quadrant has two sight vanes on one edge and there is a suspension with a hole for a silken cord with a bead (now lacking) on the front of the instrument.
On its back two concentric circles with calendar data can be seen, with an eagle – its wings spread - sitting in the centre of the rings.
Once upon a time, the bird - known for its ability to directly look at the sun - would have been able revolve. Its tail, feet and wing tips would have moved over the various scales, making it easy to calculate the date of the Easter Moon. The instrument could also tell the time of day (during sunlight hours), the length of day and night, and the height and depth of structures and objects.
Without doubt the quadrant is one of the greatest scientific instrument discoveries in the world. It is in remarkable condition for its age and it has impeccable provenance. Nothing like it has been seen at auction before.
The astrolabe quadrant is expected to fetch £60,000-100,000.
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