(Curaçao Chronicle)
Tagging along Hispaniola’s south coast from Haiti to Santo Domingo took six days, or was it eight? I hardly remember. It was treacherous and very tedious; the seas were bumpy. With a GPS-compass linked to my pilot, navigation was child’s play.
Being aboard alone with my ghosts gave me plenty of time for long monotonous dialogues. Contemplating the intricacies of navigational techniques and how navigating the globe worked from a cobweb’s viewpoint?
“Anansi, you are a man of the world, a world nomad right? You, with Akan-ancestry, in Suriname and Antilles’ exile for generations, and then in the most recent chapter, Holland as repatriation destination, you are a true global citizen.
Let me ask you a tricky question. How did you manage to find these places? How could you figure out longitude and latitude in the ocean without any coastline in view?”
“Well silly white man, of course, we always left it to the crew. You know, we were only passengers, voluntary or not. These sailors used weird instruments, weird!
“You ever studied my cobwebs; radials, and then straight connecting tangles of the silken threads? I always set out my webs for symmetry but mostly end up with asymmetrical, woven with irregular patterns, but you need the regular ones.
“Never mind, these smart sailors used our very best and most symmetrical cobwebs as grids and then looked at the sky. They superimposed reference points for the sun, and the moon and bright stars, and their bookkeepers kept extensive, minute logs of time and place for comparison! Without us, spiders, they would still be lost.
“The moon and the stars travel across the night sky, so the angle with the horizon is changing with time. Take a dinner plate and a few wires, and by measuring those angles, you know what time it is. Compare it with tables, and you also know where you are.
“Yes, Anansi of course, the dinner plate of 360 degrees became the astrolabe or a quadrant as was used in Persia, and a sextant or octant used until today in the West.”
Getting my other stowaway to give up precious secrets of navigation was a bit more difficult.
“Captain Hendrick, how did you manage to know where you were? Did you know longitude and latitude? Did you have instruments?”
With some reluctance, after a few tries and pitch black, starless nights, Captain Hendrick shared his valuable knowledge.
“Dr. Gemma Frisius, (1508) of Dokkum sold some of his secrets to the VOC and later the WIC. He was a mathematician, cartographer, and instrument maker. Using a clock for longitude was a revolutionary idea, and no such reliable device existed yet.
“Another Dutchman, Christiaan Huygens (1624-1695) also sought the solution in timekeeping. He invented the clock pendulum, which was an improvement but still sensitive to the movement of the waves.
“Finally in 1765 John Harrison, an English watchmaker, created a chronometer that was sea-resistant.”
The Amsterdam clergyman and cartographer, Plancius (1552-1622), considered another system (Simon Stevin (1548-1620), gave the theory of Plancius a mathematical foundation in his book “De Havenvinding,” 1599). For nearly a hundred years, Dutch sailors were confused and often preferred coastal routes.
Longitude, Frisius understood, could be found by comparing the time of the actual position with the time at home. The globe rotates around its axis every 24 hours, so one hour is 360 degrees divided by 24; that makes 15 degrees per hour. Each Degree divided again by 60 Minutes comes out that one Minute is equal to one Nautical Mile.
Willebrord Snellius (1580) measured the distance between Alkmaar and Bergen op Zoom with triangulation and thus got the measure of a minute, and the circumference of the globe.
But for latitude, Frisius used of the cross-staff or Jacob’s staff. By day, it was necessary to measure exactly at noon the height of the sun above the horizon with an astrolabe or cross-staff. (See Willem Blaeu (1630) of the Jordaan in Amsterdam in his mariner’s guide “Licht der Zee-vaert.”)
By Jacob Gelt Dekker
