Skip to content Accessibility statement

Sussex Declaration: Researchers authenticate American Independence parchment

News

Posted on Wednesday 4 July 2018

Analysis of the parchment manuscript of the American Declaration of Independence has shown that it is an authentic document produced in the 1780s.


Dr Sarah Fiddyment conducted protein analysis of the parchment

The Sussex Declaration, as it has become known, is the only other contemporary manuscript copy of the Declaration of Independence on parchment apart from the signed copy at the National Archives in Washington, D.C., known as the Matlack Declaration.

There are other printed parchment copies and other handwritten copies on paper but the Sussex Declaration, housed in the West Sussex Record Office, and the Matlack Declaration, are the only two ceremonial parchment manuscript copies.

Detailed scientific tests and analysis, carried out by conservation scientists at the University of York, Harvard University, British Library, and the Library of Congress including multi-spectral imaging, X-ray fluorescence, and protein testing.

Animal skins

Researchers at the University of York used a 'peptide mass fingerprinting' technique to help discriminate between the different species of animal used to make the parchment. Typically sheepskin was used to produce legal documents in England, but there is evidence of calfskin being used for important charters.

Dr Sarah Fiddyment, from the University's Department of Archaeology, said: "Using a non-invasive sampling technique, conservators were able to dry sample the document and send us the eraser crumbs which we analysed in our lab.

"We were able to identify the species of animal used to make the parchment, which in this case was sheepskin. Sheepskin was certainly the parchment of choice for legal documents, so this result is not unexpected.

"It is however, perhaps surprising that calfskin wasn't used, because this was considered higher quality and more prestigious.  For such an important document it is interesting that was not chosen."

Date revealed 

Imaging revealed a date beneath an erasure on the document. The date reads either “July 4, 178” or “July 4, 179”. It is impossible to say whether there was originally a fourth digit in the year.

Analysis of the ink shows that this lettering together with the final lettering and corrections were all written in a relatively short window of time. X-ray fluorescence analysis showed that the parchment was hung up using iron nails at some point.

The parchment was believed to have been held originally by the Third Duke of Richmond, known as the “Radical Duke” for his support of the Americans during the Revolution. The team is continuing to work on the question of when and how the parchment came to be in the UK.

Wendy Walker, West Sussex County Archivist, said: “It is a fascinating document and it has been fantastic for us to work with colleagues at Harvard, the Library of Congress, the British Library and the University of York to find out more about the story that surrounds it.”

Research newsletter

Our monthly research newsletter features a curated mix of news, events, and recent discoveries delivered straight to your inbox.

Sign up

Explore more news

News

8 May 2026

University of York students contributed more than 90,000 hours of service to the City over the last year, providing a vital economic and social boost to the region.

News

5 May 2026

Researchers are transforming access to some of the world’s oldest written records using digital technology and multilingual tools.

News

5 May 2026

Two leading academics are preparing to take up secondments to the University of York Mumbai to establish new partnerships and support new degree programmes.

News

30 April 2026

Scientists have shown that evolution has been using the same genetic ‘cheat sheet’ for over 120 million years, suggesting that life on earth may be more predictable than first imagined.

News

30 April 2026

Two infants buried in Roman York were laid to rest in costly purple cloth normally reserved for emperors and members of the aristocracy, new research reveals

Read more news