The map was made in or around 1491 by Henricus Martellus, a German cartographer working in Florence. It’s not known how many were made, but Yale owns the only surviving copy. It’s a big map, especially for its time: about 4 by 6.5 feet. “It’s a substantial map, meant to be hung on a wall,” Van Duzer said.
There are several lines of evidence for this, Van Duzer says. Columbus sailed west from the Canary Islands hoping to find a new trade route to Asia. Writings by Columbus and his son suggest that he began searching for Japan in the region where it appears on the Martellus map, and that he expected to find the island running north to south, as it does on the Martellus map, but not on any other surviving map made before his voyage. (You can see Japan floating too far off the coast of Asia in the top right corner of Martellus’s map above).
Of course, what Columbus found instead was something Martellus hadn’t known about—the New World.
What isn’t known, because of the condition of the Martellus map, is how similar the text on the two maps is. “One of the most exciting images I’ve ever seen of a map is an ultraviolet image of the Martellus map taken in the early ’60s,” Van Duzer said. “If you look at eastern Asia with natural light, if you look closely, you get a hint that there’s text there, but if you look in ultraviolet light suddenly you see that there’s text everywhere.”
Most of the text still isn’t legible in those older UV images, but some of the parts that are appear to be drawn from the travels of Marco Polo through east Asia. There are also indications of where sailors could expect to find sea monsters or pearls. “In northern Asia, Martellus talks about this race of wild people who don’t have any wine or grain but live off the flesh of deer and ride deer-like horses,” Van Duzer said. Waldseemüller copied much of this.
Van Duzer hopes to learn more about Martellus’s sources from the new images the team is creating. Scanning the map only took a day, after two and a half days of set up, he says. The team used an automated camera system developed by a digital imaging company called Megavision. The system uses LEDs to deliver light within a narrow band of wavelengths and minimize the amount of heat and light the map was exposed to. The camera has a quartz lens, which transmits ultraviolet light better than glass. The team photographed 55 overlapping tiles of the map, using 12 different types of illumination, ranging from ultraviolet to infrared.
Conceptually, the process isn’t very complicated, says team member Roger Easton, an expert on imaging historical manuscripts at the Rochester Institute of Technology. “We’re really just looking at the object under different colors of light and trying to find the combination of images that best enhance whatever it is that we’re trying to see.”
But extracting legible text from all those images will take a lot of imaging processing and analysis, and a lot of trial and error, Easton says. A combination that works on one part of the map might be useless for another part. “It depends on the details of how the map has eroded or how the color of the pigments has changed,” Easton said. “Different pigments reflect different wavelengths of light, and they deteriorate differently too.”
When the project is complete, probably sometime next year, the images will be available for scholars and the general public to examine on the website of the Beinecke Digital Library at Yale.
source: wired.com By Greg Miller