The Magnetic Compass

Alexander Neckham was a theologian and writer from St. Albans whose birthday gave him a surprising status. He was born on 8 September 1157, reportedly the same day as King Henry II's son Richard. This made Alexander's mother, Hodierna, an ideal wet nurse for the baby prince. Richard and Alexander would both be nursed by Hodierna. Hodierna was housed (and Alexander therefore raised) in the king's household and treated well.* Hodierna would even become Richard's nanny and his main source of maternal affection.

Alexander received an education similar to the young Richard, and went on to become abbot of Cirencester Abbey. He also wrote books on theology and other subjects. One of these books was his De naturis rerum ("On the nature of things"). Here's a passage:

The sailors, moreover, as they sail over the sea, when in cloudy weather they can no longer profit by the light of the sun, or when the world is wrapped up in the darkness of the shades of night, and they are ignorant to what point of the compass their ship's course is directed, they touch the magnet with a needle, which (the needle) is whirled round in a circle until, when its motion ceases, its point looks direct to the north. (1863 translation)

This is the earliest (written between 1187 and 1202) reference in Europe to the use of the magnetic compass. Beckham had recently returned from France and was specifically referring to seeing the use of the compass in the English Channel.

The Chinese were using the magnetic compass over a hundred years prior to this. It is tempting to make the leap to Chinese inventions and Marco Polo's writings, but Polo (1254-1324) lived well after Neckham wrote. It is still a strong possibility that Italian traders brought back the invention of the magnetic compass.

For the Chinese, it was a magnetized needle floating in a bowl of water and called the "South Pointing Fish." Between 1295 and 1302, Giovanni "Flavio" Gioja (if he existed: there is speculation that a typo gave credit to the wrong person) balanced the magnetized needle on a post over a compass rose and enclosed the whole thing in a box, eliminating the spillable-in-rough-seas bowl of water type.

The Muslim world, often ahead of Western Europe in scientific matters, does not make reference to the magnetic bowl-of-water compass until 1242. Muslims saw value in the device not just for marine navigation but also to determine how to face Mecca for prayer when far away from that city.

The magnetic compass allowed sailors to increase the season of safe navigation beyond the times of clear skies. More trading trips could be made during months that were typically clouded and more risky.

Alexander Neckham did more than observe a compass, however, and we'll look into him more tomorrow, including how he might have inadvertently given rise to the legend of Virgil's magic fly!

*Richard later gave Hodierna a generous pension.

The Astronomer Sultan

The Rasulids were a Sunni Muslim dynasty that ruled what is now Yemen and the Red Sea Coast of the Arabia peninsula from the early 13th century to 1454. Their third sultan, Al-Ashraf Umar II, was only sultan for less than two years, following a 46-year rule by his father, but he used his time as sultan-in-waiting to become highly educated. He understood medicine, mathematics, agriculture, and astronomy.

As an astronomer, he wrote a treatise about astrolabes (a device known to many in the east and the west) and sundials. In it, he describes the making of a qibla compass, designed to determine qibla properly wherever you are—that is, the direction toward Mecca for when you pray—a vitally important point in Islam. Al-Ashraf did not claim in the treatise that he invented it, but it is the earliest mention of a compass for determining qibla found in a medieval Islamic text, so his name is historically linked with its creation.

The qibla compass, of course, is a magnetic compass that points north. That is only the first step, however: once you find north, marks around the dial indicate major cities in which you might find yourself. The position of the city's name on the dial—if that's where you are when it is time to pray—show the compass direction from north that you must face.

Al-Ashraf also wrote one of the earliest known Islamic works on agriculture, a seven-chapter treatise that covers times for planting, cereal crops, seed crops, flowering plants, aromatic plants, vegetables, and even pest control. He lived in what is considered the Islamic Golden Age, and died in 1296.

The qibla compass is used extensively today; now, what about the magnetic compass itself? When was that discovered, and what did the Middle Ages do with it? Let's find out next time.