Attested: RC Devionisso
Where: Somewhere in Cornwall, best guess near Fowey, SX1352. This is because the Roman forts at Duriarno (Nanstallon, near Bodmin) and Statio deventiasteno (Restormel, near Lostwithiel) controlled a key trans-isthmus portage that linked the river Camel in the north with the river Fowey in the south. If Pilais can indeed be identified with the north-coast entry to the sea in Padstow Bay, it makes sense to look for a counterpart on the south coast, though no significant Roman archaeology appears to be known from the Fowey area.
Name origin: If Devionisso was created in Latin its first part could be devio ‘to deviate’, possibly appropriate to the bends in the river, whose later name Fowey (with earliest English forms like Fawe in 1210) might descend from a Latin precursor (Ekwall, 1928:164) such as vario ‘to change’. (Compare Varis). Alternatively deveho ‘to carry away’ might match its neighbour's deventiasteno. Or else maybe there was another river name like Cornwall's former Devy and Dewey, which Ekwall (1928) thought were probably originally the same as the Dyfi in Wales. See under Δηουα for the competing theories how such names might have originated, though here one must also consider Cornish devr ‘water’. The –nisso part might come from PIE *neigw- ‘to wash’, from which came English nixie ‘water spirit’, Sanskrit nedati ‘to flow’, and Greek νιζω ‘to wash’. Latin nisus was the past participle of nitor ‘to strain (giving birth, or on the toilet)’, very appropriate to the Fowey estuary, where an upland spate river slows down in a wider harbour area.
Notes: There was a powerful economic drive towards portages (plural) across the south-west peninsula of Britain, because early sailing ships faced great difficulty and danger in rounding Land's End, but there is no hard evidence to suggest which particular river systems predominated at different points in history. One candidate to be Devionisso was near St Michael's Mount, for a portage across to the river Hayle and St Ives. A better candidate was near modern Devoran, well inside Falmouth harbour, towards Truro, and not far from modern Devichoys Wood. The river Carnon there used to be navigable a long way upstream, into the heart of the Gwennap district where tin and other metals including copper have been assiduously mined since deep in prehistory, until 1620 quite large vessels could still go 3 km upstream to Bissoe. In mining districts Roman-era river configurations are hard to guess, because such prodigious quantities of mine tailings got displaced into river valleys, as in Roman Spain (Bird, 2004). Silt in the river Carnon is now many metres deep and it is fair to guess that the upper Fowey, preferred here, was also navigable much high upstream in Roman times.
Last Edited: 9 August 2016