Experts find the Lord’s Prayer on corroded 16th-century cross

The lead cross is an example of a “croix d’absolution,” a medieval funerary cross that was common in France, Germany, and England in the 16th century. Aurélien Vacheret, director of Musée Charles-de-Bruyères, the museum that loaned the cross to Georgia Tech, explained its function: 

The process of terahertz analysis began by subjecting the cross to short bursts of terahertz electromagnetic radiation, which travels on tiny waves of light. Some of these light waves bounce off the corrosive layer, but others can penetrate it. The team then measures the differences in the time it takes for the light waves to bounce back in order to determine the thickness of the corrosive layer. 

The penetrating waves are the most decisive in determining what the lead under the corrosion looks like. When they return to the scanner, they bear images of the lead, which can be collected to form a full picture. The process is very tedious and the team had to take another image every 50 microns (about half a millimeter).

The result of the analysis revealed a surprisingly legible inscription of the Pater Noster, the Latin form of the Lord’s Prayer. What’s more, the terahertz images showed parts of the inscription that would not be seen by the naked eye. The team was able to confirm this when they removed the corrosive layer during restoration. 

Professor David Citrin, leader of the project, told Georgia Tech: 

Citrin’s team has previously utilized terahertz imaging on 17th-century paintings, and is currently helping analyze ancient Roman pottery. He noted that terahertz imaging is continuing to develop, but it carries enormous potential to document some of the most delicate archaeological finds. 

Read the full report at Nature.