The Germanic diphthongs in the Continental runic inscriptions.

Runic inscriptions on the Continent, excluding Frisia, are commonly treated as representing the precursors of Old High German and Old Saxon, which are attested in manuscripts of the eighth‒eleventh centuries. If these literary languages are the result of regular sound change from a relatively homogeneous Northwest Germanic, then close study of the runic inscriptions might enable us to see some of those sound changes in progress. This paper examines the runic evidence for specific sound changes affecting the Germanic diphthongs */ai au eu/, and argues that the dialects of the inscriptions do not fit easily into a linear progression from Northwest Germanic to literary Old High German and Old Saxon.