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.
GB Historical GIS / University of Portsmouth, History of Bethesda, in Gwynedd and Caernarvonshire | Map and description, A Vision of Britain through Time.
Date accessed: 28th April 2017
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 ".