... Apollo Grannos as a god of medicinal springs cannot be severed from the Apollo Borvo of an inscription at Bourbonne-les-Bains, in the Haute-Marne, which reads Deo Apollini Borvoni et Damonae, &c.  The monuments show the name to have had several forms: Borvo and Bormo are said to be attested in central France, Bormanus in Provence, and Bormanicus in Spain; while the god's associate is in some instances called Bormana... The exact relation between the kindred forms Borvo and Bormo, together with Bormanus and Bormana, is not very clear; but it is Borvo, and not Bormo, that is re-echoed by the French Bourbon, Bourbonne; and it is Borvo that has its reflex in the vocabulary of the Celts of modern times: I allude to the Welsh berw, "a boiling," berwi, "to boil;" Irish berbaim, "I boil, cook, smelt," which are of the same origin as the Latin fervĕre and fervēre, "to boil or to be boiling hot."  It does not appear why the Gaulish word was Borvo rather than Bervo, but there can be no serious doubt as to the close kinship of the words mentioned, or the fact that the god received his name in allusion to the hot springs over the bubbling volume of which he was supposed to preside... (Lectures on the Origin and Growth of Religion as Illustrated by Celtic Heathendom, Rhys, 1892)