Oldest Dated English Scientific Instrument Has ‘Tantalizing’ Implications

Oldest Dated English Scientific Instrument Has ‘Tantalizing’ Implications

Recently discovered, the earliest dated English scientific instrument is going under the hammer at Christie’s auction house in London on Wednesday.

The palm-sized copper-alloy “horary quadrant,” which would have been used by medieval workers to determine the time of the day based on the height of the sun in the sky, is engraved with the year “1311.”

This predates the next-oldest inscribed scientific instrument, the British Museum’s latitude-finding “Chaucer Astrolabe,” by about 15 years.

Christie’s science specialist James Hyslop told Newsweek that the quadrant “is evidence of a more sophisticated workshop for scientific instruments than we’d previously thought.”

A picture of the horary quadrant
A picture of the newly discovered horary quadrant. An inscription on its reverse face dates it back to 1311—making it the earliest dated English scientific instrument.
Christie’s Images

“Medieval English instruments are incredibly rare, so any new discovery adds hugely to our knowledge of science at the time,” Hyslop added.

Moreover, Christie’s reports that the fact that one horary quadrant is known from 1311 raises the “tantalizing possibility” that the extremely rare Canterbury Astrolabe Quadrant, previously dated to 1388 based on its lunar calendar, may in fact have been made for use in 1312.

The “Master of the Chetwode Quadrant” will go to auction on December 13, and has an estimate of $130,000 to $190,000.

It will be accompanied by selection of valuable books and manuscripts, and a 17th century silver microscope made by “father of microbiology” Antonie van Leeuwenhoek, one of only 13 known to have survived.

Believed to have been introduced to Europe via Islamic Spain at some point during the late 13th century, the science underlying these instruments can be traced back to Baghdad during the 9th and 10th centuries.

Quite unlike the system of time we use today, horary quadrants divided up the daytime into 12 “temporal” or “unequal” hours that vary with the time of year.

Using the instrument, the first hour begins at daybreak, midday comes at the end of the sixth hour, and sunset comes at the end of the twelfth hour.

Given this, each hour is longer in the summer than in the winter, which would have helped workers to make the most use of precious daylight.

“These quadrants were probably the tools of merchants, senior churchmen and scholars,” Hyslop said in a statement on Christie’s website. “The knowledge they provided would have revolutionized the way people in the Middle Ages lived.”

Despite its humble usage, horary quadrants are also known to have made it into the hands of the upper echelons of society.

The “She-Wolf of France,” Queen Isabella, wife to King Edward II of England, is known to have been gifted several of the instruments in 1358 by a monk of the Abbey of St Albans Cathedral.

Records note that “William Orologer, monk of St Alban’s [brought] to the lady queen several quadrants of copper from the like gift by his own hands on the same day.”

The newly discovered horary quadrant
A picture of the main face of the horary quadrant. The palm-sized, copper-alloy plate is engraved with six unequal hour lines, which would have been used to tell the time.
Christie’s Images

Philipp Nothaft is a historian at the University of Oxford, England, whose focus lies on the practice of astronomy and chronology during medieval and early modern Europe.

The instrument being sold in the auction, he told Newsweek, is a universal horary quadrant of the type known as a “quadrans vetus.

“Its primary function was to infer the time of day from the measured solar altitude via the engraved hour lines,” Nothaft said. “The conversion of altitude into time relies on a trigonometric formula that is exact only at the equator, but provides acceptable approximations at most other latitudes.”

In addition to helping to tell the time, Nothaft notes, the quadrant can also be used to solve mathematical problems involving the measurement of distances, depths and heights, using the “shadow square” beneath the hour lines.

A close-up of the horary quadrant's reverse
A close-up of the reverse face of the horary quadrant. This side features a revolving index pointer,
Christie’s Images

“Horary quadrants were one of many portable time-measuring devices known in medieval Europe,” Nothaft told Newsweek. “They are frequently described in manuscripts, but only a very small number of specimens have actually survived from the Middle Ages.”

He added: “The quadrans vetus enjoyed particular popularity in the 13th and 14th centuries and is known to have existed in two basic variants, depending on whether or not the instrument included a moveable cursor for finding the daily solar declination and noon altitude.”

The solar declination is the angle between the direction from the Earth’s center to the middle of the Sun’s disk and the equatorial plane. It can be used, for example, to help determine the latitude of a ship at sea.

The microscope credited to Antoni van Leeuwenhoek
Front and reverse images of the microscope credited to Antoni van Leeuwenhoek, the “father of microbiology”. The instrument—which is also being actioned this week—is one of only 13 known to have survived.
Christie’s Images

The newly-discovered quadrant is also noted to bear “remarkable similarities” to another.

This instrument was unearthed in a field in Chetwode, Buckinghamshire, England, by metal detectorist Simon Neal nearly a decade ago.

According to Christie’s, who also auctioned off that find back in late 2015, both quadrants are similar in composition, shape, and the style of engraving.

This suggests that they may have been produced in the same workshop, if not by the very same hand, in the early 14th century.

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