A limestone vessel (pictured below) believed to be a cresset (or lamp) was recently examined using organic residue analysis. It was found in a post-medieval soil dump during excavations by Urban Archaeology at Dulverton House, Gloucester, in 2020 (see CA 390). It is believed that this may be the first stone cresset to be assessed in such way, with the analysis demonstrating that it was indeed used as a light source.
Medieval stone cressets are currently being researched by Dr Ruth Shaffrey and they are somewhat enigmatic artefacts. While they are found mostly in monastic or high-status contexts, they are often rather crudely finished. They also appear in a range of forms, from tall pedestals or multi-socketed designs to small and block-like ones like the Dulverton example. As most cressets from Britain do not have any evidence of residue on them, it had previously been thought that they may have been used to hold ceramic lamps, which are more common in the archaeological record, rather than being a light source in their own right. A few examples, however, including the Dulverton one, have evidence of scorching with burnt-on deposits on the inside walls.
To learn more about the object’s use, a team from the University of Bristol, led by Dr Julie Dunne, sampled the residue to determine its composition. Lipid analysis found that at least half of the substance was made using ruminant (that is, cattle, sheep, or goat) fat, probably tallow, while the other half was made from non-ruminant products, possibly from the lard of pigs, chickens, or rabbits. These contents indicate that this particular cresset, at least, was used directly as a light source.
This raises the question, then, of why stone cressets were sometimes used when ceramic lamps appear to be more common. Their crude finish and the fact they are often made from the same stone used for nearby structures suggests that they may have been created out of convenience, using leftover building material. Additionally, they first appear in the archaeological record around the 9th century and endure beyond the 14th century, when ceramic lamps were declining in use. Because of this, the team believe that, although the Dulverton cresset was found in a post-medieval context, the artefact itself is probably medieval in origin. It may be that it came from the nearby Abbey of St Peter’s, which was in use from AD 1089 until the Dissolution of the Monasteries, when it was converted into Gloucester Cathedral.