Library of Congress Blogs: “It’s not often that the Library has a chance to acquire a portolan chart — an early nautical map, hand drawn on animal skin, that explorers used to navigate the seas. Not many still exist, so the Library leaped at the chance last fall to acquire a circa 1560 portolan depicting the North American East Coast by Portuguese cartographer Bartolomeu Velho. Extending from the coastline of what is now Texas, around the Gulf of Mexico to Florida then up the entire present-day East Coast, the original map and a high-resolution enhanced version, produced by the Preservation Research and Testing Division, are now on the Library’s website. The latter reveals previously illegible place names — including some of the earliest known uses of names by European explorers for locations on the Atlantic coast. The enhanced map, producing by multispectral imaging, illuminates things that the human eye cannot see. It’s the first time the Library has posted a PRTD-enhanced image. “It’s exciting,” Fenella France, PRTD’s chief, said of the web availability of the image. “It is now a resource for scholars from anywhere.” It required coordination between two Library’s divisions — Geography and Map and PRTD. PRTD’s work, said G&M cartographic acquisitions specialist Robert Morris, “added even more value to what was already a valuable chart.” For more than 15 years, PRTD has used noninvasive techniques, chief among them multispectral imaging, to glean information from Library collection items that the human eye cannot see. Multispectral imaging involves digitally photographing an object at multiple wavelengths…”