How a medieval timepiece, a miniature microscope and a thesis changed our understanding of the world

In front of Christie’s science and natural history specialist James Hyslop are three objects that he says fundamentally changed the way we understand the world around us. ‘They might look quite ordinary to the untrained eye,’ he explains, ‘but they each actually represent a seismic shift in terms of scientific knowledge.’

The earliest dated English scientific instrument

The oldest is a particularly rare type of ‘horary’ quadrant, which is inscribed with the year 1311, making it the earliest dated English scientific instrument known to exist.

This slice of copper plate has various engraved scales that could be used to calculate the height of an object, the altitude of the sun, and, with a spinning index pointer, the date of the next Sunday after the first full moon following the vernal equinox — Easter to Christians.

It also contains a sundial that tells the time, which in medieval England was commonly divided into 12 hour-long segments between sunrise and sunset. This meant that each hour was longer in summer than in winter — which was useful when daylight was crucial to working the land.

The ingenious science behind this device, which remained in use in one form or another for nearly a millennium, can be traced back to a manuscript produced in Baghdad in the 9th or 10th century. The city was a cosmopolitan centre of learning, which fed into Europe through Al-Andalus, the area of the Iberian peninsula that was under Muslim rule between the 8th and 15th centuries.

Quadrants like this are first recorded in Montpellier during the 13th century, described by Prophatius, an astronomer and translator of Arabic treatises. By the 1350s, their popularity had spread to the uppermost echelons of society: Queen Isabella, the wife of England’s King Edward II, was gifted several horary quadrants by William Orologer, a monk of the Abbey of St Albans Cathedral.

‘These quadrants were probably the tools of merchants, senior churchmen and scholars,’ explains Hyslop. ‘The knowledge they provided would have revolutionised the way people in the Middle Ages lived.’

While their use was probably widespread, only a handful of early examples survive. The two best-known date from the late 14th and 16th centuries and belong to the British Museum in London and the Museo Galileo in Florence. A third was discovered by a metal detectorist in 2015 near an Augustinian priory founded in 1244 in Buckinghamshire, England. The similarities between that quadrant and the one being offered at Christie’s suggest they could have come from the same workshop — and might possibly even have been made by the same anonymous master.

Antoni van Leeuwenhoek’s microscope

The second object is a rare survival of an early form of microscope, created by the Dutchman Antoni van Leeuwenhoek around the year 1700.

Born in Delft in 1632, Van Leeuwenhoek is known as the father of microbiology. He gained his first experience of microscopy examining linens through a magnifying glass. In 1675, using one of his own homemade devices to study plaque scraped from his teeth, he became the first person to observe bacteria.

Thanks to his clandestine way of working, the scientist held a virtual monopoly over microscopic discovery in the 17th century. Nevertheless, in 1680 he was elected to the Royal Society in London. He also produced more than 300 microscopes, donating examples to Tsar Peter the Great of Russia and Queen Mary of England. Their survival rate, however, is low. The discovery of this one, which has the highest-powered magnification lens of all the extant microscopes (285x), brings the total of today’s known examples to just 13.

‘Each one was made for a specific purpose, whether viewing the wings of an insect or protozoa,’ explains Hyslop. ‘But because they don’t look like obvious treasures, the majority were discarded or melted down. The few that have survived provide evidence of how important they were for our knowledge of the natural world.’

It has been suggested that Van Leeuwenhoek was friends with another prominent inhabitant of Delft: Johannes Vermeer. The two were baptised just four days apart in a city of only 24,000 people, and Van Leeuwenhoek is thought by some to be the sitter in Vermeer’s paintings The Geographer and The Astronomer.

Claude Shannon’s master’s thesis

The final object is a copy of what has been called ‘the most important, and also the most famous, master’s thesis of the century’. Completed in 1937 by the 21-year-old American mathematics and engineering student Claude Shannon (1916-2001), this document proposed that relay circuits could perform complex mathematical operations. This meant, he realised, that it would be possible to create complex calculating machines using electrical switches — a proposal that would become the foundation of modern computing.

With the outbreak of the Second World War, Shannon was hired by America’s National Defense Research Committee, where his work on cryptography proved useful to the Allies. Famously, over lunch in the cafeteria, he also shared his ideas with the British mathematician Alan Turing, whose efforts at Bletchley Park in England previously resulted in the cracking of German naval ciphers.

After the war, Shannon worked at the Massachusetts Institute of Technology, where he is credited with pioneering the science behind artificial learning and personal computers. Among his inventions were some of the first machines to juggle, play chess and solve a Rubik’s Cube.

‘Shannon’s understanding of logic’s application in circuit boards was a huge leap forward in terms of our understanding of what machines are capable of,’ says Hyslop. ‘He and Turing provided the framework for the digital computing revolution — and this document is a keystone of that.’

Explore art from antiquity to the 21st century at Classic Week, until 15 December 2023 at Christie’s in London