In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Bethesda like this:
BETHESDA, a village in Llandwrog parish, Carnarvonshire; on the coast, 5 miles SW of Carnarvon.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Bethesda has changed, please see our redistricted information for the modern district of Gwynedd. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Bethesda and units named after it.
GB Historical GIS / University of Portsmouth, History of Bethesda, in Gwynedd and Caernarvonshire | Map and description, A Vision of Britain through Time.
Date accessed: 09th December 2016
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Bethesda".