New Method for Dating Maps

Cool. Perhaps this will allow dating of all those controversial maps!

A new and relatively simple method for discovering the date when centuries-old art prints and books were produced has been developed at Penn State. The method could reveal long-sought information about thousands of undated works printed on hand-operated presses prior to the development of modern printing methods in the mid-19th century, including works by Rembrandt and Shakespeare.

Hedges, a world-renowned biologist whose hobby involves Renaissance prints and maps, developed his "print clock" method by first measuring time-related changes in 2,674 Renaissance works. He found that the number of breaks in the lines of images printed from woodblock carvings increased over time, while the image intensity became more pale in copperplate prints...

Hedges' woodblock studies involved four editions of Bordone's Isolario, an atlas containing maps of islands. The print date was known for three of the editions, published in 1528, 1534, and 1547, but the age of the undated book has been debated for nearly 200 years, with estimates ranging from 1537 to 1570...

In addition, Hedges used his print-clock technique to calculate the day on which there were no cracks in the wood, revealing the date when the artist finished carving the woodblock. "This estimate of the date the woodblock was carved seemed odd because it was ten years before the date of the first print, but it turned out that the carving date agreed with the historical records, which place the cartography in that earlier decade," Hedges says.