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.