An anonymous bidder has paid £138,000 for a rare 14th Century scientific instrument uncovered during building work in Kent.
The astrolabe quadrant - dubbed the "pocket calculator" of its age - was sold at Bonhams in London on Wednesday.
Made in England in 1388, the device was used for telling the time, mapping the stars and taking measurements.
It was found in Canterbury in 2005, and is said to be one of only eight examples in the world.
An anonymous telephone bidder paid £115,000 but this rises to £138,000 with auction commission and tax.
The brass instrument was found during excavations for an extension to a restaurant.
The site of the find is known as the House of Agnes, a 17th Century inn on the main road out of Canterbury to London.
Jon Baddeley, director of Scientific Instruments for Bonhams, said: "It was a privilege to handle such an historically important artefact.
"It is extraordinarily rare to find a scientific instrument of such an early date and impeccable provenance at auction."