Endeavour cannon, circa 1750s

Collection
National Museum of Australia, Canberra, ACT, Australia. Currently on loan to the Australian National Maritime Museum, Sydney, NSW, Australia.

Object Name
Cannon

Object/Collection Description
Endeavour cannon, 18th century, 4-pounder short cast iron. One of six cannon thrown overboard on 11 June 1770 when Cook’s ship Endeavour struck a coral reef south-east of what is now Cooktown. Good Condition. Dimensions 1000 mm x 445 mm x 95 mm.

Endeavour cannon, circa 1750s

In 1768, England sent an expedition to Tahiti to chart the transit of Venus across the sun. A brilliant Royal Navy navigator and map maker named James Cook was put in charge of the expedition on the converted coal carrier HMS Endeavour. After completing the astronomical task, Cook set out to find if there was a Great South Land, as navigators had believed for hundreds of years. After circumnavigating New Zealand, Cook’s expedition sailed west for Van Diemen’s Land (Tasmania) but winds forced the Endeavour north and the expedition came upon the east coast of Australia in April 1770. For the next four months, Cook mapped the east coast of Australia from Eden to the Gulf of Carpentaria. At a brief and simple ceremony at Botany Bay, Cook named the entire east coast of Australia New South Wales.

In June 1770 the Endeavour was damaged when it struck part of the Great Barrier Reef. In an effort to float it off the reef by reducing weight, Cook ordered six cannons and other heavy items thrown overboard, charting the location of this incident (possibly for later recovery or perhaps simply because he kept detailed records of all aspects of his voyages). In 1969 researchers, using a magnetometer to scan the reef in the area shown on Cook’s charts, discovered the six cast iron cannon. Invisible under two centuries of coral growth, underwater explosives were used to free the cannons from the coral. The wooden stocks, if they survived, were not retrieved.

In the same year, an expedition from the American Academy of Natural Sciences successfully located and raised the six cannons which are now displayed in London, Wellington, Philadelphia, Cooktown and two in Sydney (at the Australian National Maritime Museum).

After recovery from the sea floor, the cannons were transported in sea water then left to soak in a sea water solution with 10% formalin to kill any bacteria present. Hammers were used to remove hard coral from the surface. Core drilling of the cannons’ bores recovered wadding, cannon balls and the residue of powder charge from some of the cannons!

The cannons were then placed in 2% NaOH for a week during which time gas evolved from the surface which was found to be 80% hydrogen. Using the cast iron cannons as the cathode and mild steel anodes (including a bar inserted inside the cannon bore for good current distribution), electrolytic treatment in 2% NaOH was maintained for many weeks. A current density of around 10 amps per square metre was used (less would be too slow, more would cause damage to the artefact surface by hydrogen gas bubbling). This required approximately 4 volts across each bath. After a two-week period, during which the baths’ chloride concentrations rose from 0.008M (300ppm) to 0.013M (460ppm), the solution was discarded and replaced.

Subsequently, baths were changed weekly and the cannons washed with fresh water at each change. It took many weeks before the chloride concentration levelled out at around 5 x 10-4 M (20ppm). During this time brown rust patches were seen to disappear and the surface layers hardened.

After electrolytic treatment, prolonged washing was carried out to remove remaining chloride and hydroxide. This took five months with fortnightly changes using distilled water with chromate ions (8.7 x 10-3M), pH > 8.5. (An iron oxide, chromic oxide surface protective layer forms).

The cannons were dried for 48 hours at 120° C. They were then immersed in molten microcrystalline wax which was kept at 135° C for five days until no gas bubbles were evident. Allowing the wax to cool to just above melting point (80° C) before removing the cannons, ensured maximum penetration of wax. This wax treatment is reversible. This is significant as it allows for the possibility of better treatments in the future.

The cannon has historic value as it is from the HMS Endeavour, the vessel used by James Cook to chart the east coast of Australia. Cook is one of the greatest navigators and cartographers in European exploration history.

The cannon has aesthetic significance in that it is well enough preserved for the Royal Navy broad arrow, the British Royal emblem and other identifying features to be clearly visible. This also gives the cannon significance for researchers. These symbols are code used by the British Royal Armourers to document not only the repairs and alterations made to the cannon over time but also where this work took place.

The cannon has significant social value, being an iconic symbol of Captain James Cook, the person responsible for the foundation of modern Australia as we know it.

The object is well provenanced and documented. The cannon is extremely rare. It is one of six cannon discarded by Cook on the reef near Cooktown.

The object represents a time early in Australia’s history when England was still establishing itself in the Pacific and exploring the new environment. The cannon also represents the coming of Europeans to Aboriginal Australia. With the distinctly classic shape of a small ship’s cannon, it is instantly recognisable as a symbol of navigation and exploration.

The cannon is in excellent condition.

The cannon interprets the themes of British exploration and colonial expansion into the Pacific and the achievements of James Cook in the European discovery and mapping of the east Australian coast. The cannon can be found in the Navigators exhibition in the Australian National Maritime Museum. The original cast iron cannon has been placed in the recreated wooden stocks to show how it might have appeared on the decks of the HMS Endeavour.

Broese, F.
Island Nation: Australia’s Maritime Heritage,
Sydney, 1998.

Coupe, S. & Andrews, M.
Their Ghosts may be heard: Australia to 1900,
Longman Cheshire, Sydney, 1992.

Significance: A guide to assessing the significance of cultural heritage objects and collections,
Heritage Collections Council. 2001.

Steven, M.
First Impressions: The British Discovery of Australia,
London, UK, 1988.

Websites

www.anmm.gov.au/site/page.cfm?u=178&c=34

www.nma.gov.au

Edited by Helen Cumming