Oxford History: The University of Oxford

The River Thames or the Isis?

It used to be thought that the ancient name for the Thames, Tamesis or Thamesis, came from a combination of Thame and Isis, but this is no longer given any credit, although the name Isis is probably an abbreviation for Tamesis. In the fourteenth century Ranulphus Higden, a monk of Chester, wrote that it was possible that the word Thamesis was composed from the names of two rivers, the Thama and the Ysa (or Usa), and Peter Ackroyd thinks that is likely that Ysa/Usa is from the Celtic isa/esa, and that the word Ysa became Isis.

Until the twentieth century, the name Isis was used for the River Thames from its source in the Cotswolds until it was joined by the confusingly named River Thame at Dorchester-on-Thames. Today it usually only refers to the section of the river that flows through Oxford.

1st–4th centuries AD


The man who inscribed Tamesubugus fe[cit] on a pottery item he made at the kilns on the site of the present Churchill Hospital considered that he lived near the Thames, not the Isis. The following report by the East Oxford Archaeology Project explains the interpretation of the inscription (where the letter E is represented by II)

Seventeenth century

John Leland in Commentarii in Cygneam Cantionem (1658) wrote:

… quorum [fluviorum] qui primus, Isidis vadum, vulgo Oxforde, sed corrupte pro Ouseforde

[… of which rivers the foremost, the shallow water/ford of Isis, commonly Oxforde, but wrongly for Ouseforde]

Eighteenth century

This extract from Jackson's Oxford Journal of 21 August 1756 refers to the “River Isis” as far south-west as Hart's Weir near Appleton (then in Berkshire): 

JOJ 21 Aug 1756

This extract from Jackson's Oxford Journal of 5 July 1777 calls it the Isis even further upstream at Cricklade in Wiltshire

JOJ 5 July 1777

By 1785 there was an authority called “Thames and Isis Navigation”. The article below from Jackson's Oxford Journal of 15 September 1787 refers to an Act of Parliament for improving and completing the navigation of the Rivers Thames and Isis from the City of London to Cricklade in Wiltshire. The river is evidently called the Thames at the London end and the Isis at the Wiltshire end:

JOJ 15 Sep 1787

Nineteenth Century

This map of 1900 still uses the description “River Thames or Isis“ upstream from Oxford as far as Newbridge, while downstream the last use is here, and then after Dorchester it is simply the River Thames.

Near Folly Bridge there was an Isis Street (from 44 St Aldate's Street) by 1843; but there was also a Thames Street nearby (from 50 St Aldate's Street

Isis today

Today the name Isis is almost exclusively used for the part of the river that flows through the City of Oxford, particularly by the University. It is nearly always used in the context of rowing, and its reserve boat in the Boat Race was given the name Isis in 1865.

The name Isis fell somewhat out of favour when the militant group Islamic State of Iraq and al-Sham (Isis) started to dominate the news in 2014. The following organisations in Oxford changed their names:

  • The Isis Guest House in the Iffley Road (which now belongs to St Edmund Hall and only does summer lets)
    simply expanded its name Isis to the full ancient spelling, Tamesis Guest House
  • The Isis Academy is now the Iffley Academy
  • Isis Hair in Headington is now Ice Hair
  • Isis Innovation is now now Oxford University Innovation
  • Isis Estate Agents are now Wallers of Oxford

The following Oxfordshire institutions kept the name Isis:

  • The Isis Boat House
  • The Isis reserve crew in the Boat Race
  • The Isis House Care Home, Iffley
  • Isis Lodge (Freemasons), Nuneham Courtenay
  • The university magazine Isis

The following business adjusted its name:

  • The Isis Farmhouse pub became the Isis River Farmhouse pub

This notice under the railway bridge to the west of Oxford (photographed in 2023) refers to the River Isis:

Reference to "River Isis" on railway bridge

© Stephanie Jenkins

Last updated: 30 September, 2023

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