Mardi Gras Shipwreck Project

Project Sponsor: Minerals Management Service (MMS), Okeanos Gas Gathering Company (OGGC)

Time period: early 19th century

Excavation: 2007

Conservation: 2007-2016

Site History and Fieldwork

In 2002, an oilfield inspection crew working for OGGC discovered a shipwreck off the coast of Louisiana at a depth of about 4000 feet below the surface. In 2007, funded by OGGC under an agreement with MMS, Texas A&M University led an excavation of the deepest archaeological site at the time, using ROVs to retrieve diagnostic artifacts to attempt to identify the ship. Its identity is still unknown, but the artifact assemblage indicates it likely wrecked between 1810-1820–perhaps a War of 1812 gun runner or British trader.

Octant

An octant is a navigational instrument used to determine latitude from around the 1730’s onward. The first thing you might notice about this octant is that it’s incomplete. The octant gets its name because the shape of the instrument makes up an eighth of a circle. There is an obvious culprit: we can see by the bore holes in the wood that this octant served as a meal for teredo navalis, the shipworm. What is left is part of the frame, the pivot from which an arm would move to mark a degree along an arc, a mirror, and a set of three index shades used to reduce the glare of the sun, as the instrument required the navigator to look at the sun.

Like most composite artifacts, the first step after documentation was disassembly. Separating out artifacts by material components allows us to fully clean the artifacts and treat each material according to its needs. The wood and glass components were treated using silicone oil, and the metal components were treated using electrolytic reduction. After cleaning faint marks were visible on one of the cupreous components – the clearest marking being a “27”, possibly indicating the number in a series of octants made. The presence of these marks could help identify the maker.

Coffee Mill

This small coffee grinding mill is composed of three materials: the wood box, with projections that indicate there was once a drawer to collect grounds; a copper alloy bowl; and an iron grinding apparatus, which was fully encased in concretion when it arrived at CRL. Eighteenth-century mills were usually made of turned exotic hardwood, and fully cast iron mills were introduced in 1815, so this mill seems to be an intermediate version of these better known types. The majority of the artifacts from the site have manufacturing dates between 1780 and 1820, and this mill fits this range as well.

All of the components were separated for treatment. The wood was dehydrated in solvents then treated with silicone oil. The bowl was treated using electrolytic reduction. X-rays showed that the concreted iron grinder had completely corroded, so conservators cleaned out the void left behind and poured in epoxy to create a facsimile.

Telescope

The telescope is a composite made of wood, brass, and glass. In order to ensure each component was treated to the best of our abilities, the telescope was completely disassembled. The metal was treated using electrolytic reduction and the wood and glass were treated using silicone oil. Once treatment was complete, the telescope was reassembled.

During disassembly, we were excited to find a very clear makers mark:

T. HARRIS & SON LONDON

DAY OR NIGHT

This telescope would have been particularly valuable to watch officers stationed on deck at night, as it has a relatively large objective lens to collect the maximum amount of light. Thomas Harris began his business in 1780, and his son William joined him in 1806; they were known as opticians and makers of globes, mathematical instruments, and telescopes.

Conservators at work on the Mardi Gras Shipwreck’s artifacts

External Resources

Florida Public Archaeology Network (FPAN) page on the Mardi Gras Shipwreck