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- [Voiceover] Tree rings are rich with history and can reveal the exact age and geographic origin of a tree trunk or a piece of wood. The scientific analysis of tree ring patterns is known as dendrochronology, and was used to learn more about the cabinet's wood. Only certain types of wood can be analyzed with dendrochronology. In the case of the cabinet, the oak interior was most suitable. But the end grain of these oak panels, where the tree pattern is visible, was inaccessible. So to examine the hidden tree ring pattern of the interior, an innovative method of x-raying was devised. To begin, parts of the cabinet were carefully disassembled, transferred to the museum's x-ray laboratory and placed on a rotating table. For dendrochronology to be effective, the rings must be measured very accurately. Once the tree rings were perfectly aligned, the image was recorded on x-ray film. The tree rings were measured from this high resolution image and these results, along with many other samples, were analyzed by a dendrochronologist, who compared the tree ring measurements to weather patterns in different regions, going back in history. The dendrochronologist concluded that these oak panels came from a tree that grew in the region of Burgundy, in eastern France, and was cut down in 1574, six years before the cabinet was made. Even the cabinet's smallest details had much to reveal about its origins. The middle drawer is lined with a silk and linen fabric, which is held in place by rose head tacks. Scientific analysis could tell us whether these tacks are from the 16th century or are later reproductions. A loose, broken tack discovered inside the cabinet was prepared for analysis. It was embedded in liquid resin that was hardened under blue light. The embedded tack was then cut and polished. To determine the tack's composition, it was analyzed using an x-ray technique known as X-ray fluorescence or XRF. The XRF instrument creates a spectrum with each line representing a different chemical element. The spectrum showed that the tack was made of brass, but also contained significant traces of other metals. Such impure brass was commonplace in the 1500s, but not in more recent times. Next, to determine how the tack was made it was examined under an optical microscope. Getty scientists observed that the tack had a very even and rounded crystal structure, which indicated that the metal was cast into a mold and then allowed to cool naturally. A common working method in the 1500s. A tack that had been made more recently, would probably have been hammered or stamped resulting in a very different crystal structure. The microscope also revealed an interesting layer on the surface of the tack. To identify the composition of this surface coating, a scanning electron microscope was used. The upper layer was targeted and analyzed with an electron beam. The spectrum produced by the microscope showed that the layer was primarily composed of the element tin. As you can see in this replica, the thin layer of tin was used to imitate the shiny appearance of silver. These discoveries about the manufacture and chemical composition of the tacks, enabled Getty scientists to conclude that they are authentic and date back to the fabrication of the cabinet in 1580.