What makes a 300-year-old pocket watch tick ?

salvaged pocket watch have been revealed by cutting-Trustees of NMS edge X-ray analysisTrustees of NMS

By Jo Marchant - Nature.com

State-of-the-art X-ray scans have revealed the internal mechanisms of a corroded, barnacle-covered pocket watch recovered from a seventeenth-century wreck.

The watch looks little more than a lump of rock from the outside, but the scans show that the mechanism inside is beautifully preserved, from delicate cogwheels and Egyptian-style pillars to the maker's inscription.

Researchers from the National Museums Scotland in Edinburgh used the images to construct a three-dimensional virtual reconstruction of the watch's lost workings. 

They hope to use the technique to probe the internal structure of other archaeological artefacts, especially those salvaged from underwater sites.

The watch and three-dimensional reconstruction are now on display in the Treasured exhibition of the National Museum of Scotland until 2011.

The watch was found on a wreck believed to be the Swan — a small warship that sank off the west coast of Scotland during the English Civil War. She formed part of Oliver Cromwell's forces that attacked the Royalist stronghold of Duart Castle in Mull, UK, but succumbed to a violent gale on 13 September 1653.

A naval diver discovered the wreck in the 1970s, and it was excavated in the 1990s. Salvaged artefacts including the pocket watch, a hoard of silver coins, cast iron guns and an ornate sword hilt were taken to the National Museum of Scotland.