At a time when many aspects of flight monitoring are digital and computerised, it may surprise some to learn that one of the most essential devices for flight is a device that has been used for over 110 years. At the same time, the lack of correct usage (or a defective device) has been speculated to have played a part in some of the most intriguing mysteries of aviation, such as the disappearance of the L’Oiseau Blanc, Amelia Earhart, and the 5 Grumman TBM Avengers whose loss helped sensationalize the story of the Bermuda Triangle. From backpackers to boats to Boeing jets, there’s few more essential and reliable tools than the compass; however, the word has had a long and varied usage before it ever got around to telling us which way North is.
Looking first at the word itself, compass comes from the Old French compas, meaning ‘circle, radius or size, extent’, which is derived from the Latin compassare, meaning literally ‘to pace out’, (cum ‘with’ and passus ‘a step’). While the first actual compass, created for the purpose of divination, dates to Han dynasty China, and was made of lodestone, a compass intended for navigation wasn’t actually created until the 11th century, during the Song dynasty.
That being said, the first actual use of our word was meant to denote simply skill or ingenuity, as can be seen in the Middle English work, The Castle of Love, which, circa 1320, mentions: “A throne of white ivory…with compass curled and ingeniously carved.”
Within 2 decades though, the term was being used, interestingly, to define a circumference, or anything circular in shape, as noted in the poem, The Prick of Conscience (1340), attributed to Richard Rolle, which states that: “the earth … is but also a point in the middle of a compass”
In the 1382 Wycliffite Bible, our term came to be used to denote a circular journey or movement: in Romans 15:19, it is written that: “From Jerusalem by compass until unto Illyricum, I have fulfilled the gospel of Christ.”
Interestingly, these uses of compass to demonstrate a circular pattern all predate the concept of the term as a mathematical instrument (2 equal legs connected by a joint). This usage only entered English in the late 1300s, via John Trevisa’s translation of Ranulf Higden’s Polychronicon, which only briefly mentions that: “ [Perdix] made the first compass.”
The usage of the term before reaching our modern understanding of a magnetic compass can be found in the circa 1400 poem Sir Gawain and the Green Knight, where Sir Gawain meets a lady described as “the fairest in feature, in flesh and complexion, and in compass and colour and ways, of all others”, and our word is simply used to convey a measure or proportion.
Finally arriving at the item and term usage that we know today, the satirical poem, Cock Lorell’s Bote (1518?), speaks of how, on the ship, “Some the anchor laid..One kept the compass and watched our glass.”, referring specifically to the mariner’s compass, which would spawn all of the derivatives that we know today. As for how the navigational device came to be named after defined objects that aren’t really associated with it, well, that’s mainly due to the mariner’s compass design: with being round/spherical and initially having legs resembling the mathematical instrument, it resembled several aspects/previous definitions of the word, therefore, the name stuck.