A navigational compass

As described in the grand narratives of the history of technology, Europe in the later middle ages straddles the era during which alembics, sundials, clocks, astrolabes, navigational compasses, and similar technological devices began to enter everyday use. As noted in a previous feature essay, alembics are frequently attested in the DALME collections, especially in records from the Crown of Aragon and the region of Greater Provence. In the collection, there are some rare but interesting references to sundials and clocks, which can be found in Latin-language records by searching for words beginning with "horolog-" "orolog-," and "rellog-" or "relog-." We expect to dedicate a future essay to these time-keeping devices.

The only reference to an astrolabe discovered to date, in turn, is a fictitious one, for it appears in the humorous poem entitled "Neujahrsgruß," published in 1510. In this text, which is one of the so-called "Poems of Household Goods" contributed to the DALME collections by Dr. Marco Tomaszewski, a man tells a woman, presumably his wife, about all the household goods that he is giving to her as a New Year's present, including a compass, a sundial, and an astrolabe with the twelve signs of the Zodiac set around it (p. 12). An object not infrequently found in Latin-language records was described by means of the noun compas, although most or all of these phrases probably referred to the technical instrument that makes it possible to draw circles or accurately measure small distances rather than a compass needle or navigational compass. The latter was more typically called an acus in later medieval Latin.

As of this writing, we have found two inventories, in addition to the reference in the "Neujahrsgruß," that refer unambiguously to compass needles. The inventory of Bartholomeus Egidii, who died in Marseille in or shortly before September of 1359, is the earliest of these. In an unusual observation written in the first-person plural that appears toward the end of the inventory, the compilers reported the following discovery they had made in one of the bedrooms: "In this bedroom, there is a chest which was locked, and when we unlocked it, we found two clocks. Also, a needle for navigational purposes (item unum acum unum (sic) ad opud navigandi)."

The second, also from Marseille, appears in the 1422 inventory of the late Johannes Isnardi, who was originally from the village of Six Fours near Toulon. His wife, Andriveta, appeared in court to reclaim her dowry of 100 l. from his bankrupt estate, and the bankruptcy court undertook to compile an inventory of Johannes's assets. Although his goods were relatively rudimentary, they did include a good-quality seaman's chest (unam capssiam bonam navigandi) and a fisherman's boat, almost certainly a type of vessel known as a lahut, which was furnished with four oars, a mast, a spar, and a sail. Clearly, Johannes was a man accustomed to the sea. The short list of goods also included a cuirass or breastplate. From these references we can hazard some guesses about his lifestyle. The presence of the armor and the seaman's chest suggest very strongly that Johannes was accustomed to hiring out his services for extended periods of time on war galleys. In the moments between campaigns, he supplemented his income by fishing.

The cuirass, valued at 2 florins and 6 gros, was found in a caisson (a type of chest). Along with it, the compilers of the inventory discovered unum orologium et unam agulham navigandi. In this instance, the word orologium almost certainly refers to a sundial. Although mechanical clocks were being manufactured in Europe by 1422, they were still sufficiently new that those who came across them while compiling inventories were inclined to provide longer descriptive phrases in order to disambiguate mechanical clocks from sundials. In 1422, in other words, a simple reference to an orologium without any further description probably means a sundial. The agulham navigandi refers unambiguously to a compass needle. In this case, the notary may not have known the Latin word for "needle," so he instead used the Occitan word agulha (modern French aiguille), a distant vernacular descendant of the Latin acus. Since agulha could refer to any needle, he added the gerundive navigandi, which literally means "for the purpose of sailing," although the verb also had the sense of "directing" or "steering." To judge by the appraisal, there was nothing special about either the sundial or the compass needle, since together they were valued only 2 gros, no more than a day's wages.

What is striking about this inventory is that a navigational compass was found in close proximity to a sundial. Were they linked somehow? The sophisticated marine chronometer only began to be used for fixing longitude in the eighteenth century. That said, an ivory diptych produced in Nuremberg in the late fifteenth century, shown here, combines a sundial with a well for mounting a magnetic compass, though the latter is now empty. These phrases, in other words, may well point to similar devices, or similar situations where sundials and navigational compasses were being used together, by the fourteenth or early fifteenth centuries. Please write to us if you have any further information to share about this.