When this consonantal u (English w as seen in words borrowed very early from Latin like wall and wine) passed into the sound of English v (labio-dental) is not certain, but Germanic words borrowed into Latin in the 5th century A.D.
V is therefore a voiced labio-dental spirant, the breath escaping through a very narrow slit between the lower lip and the upper teeth.
In the middle of words between vowels f was originally regularly voiced: life, lives; wife, wives, &c. The Latin V, however, was not a labio-dental spirant like the English v, but a bi-labial semivowel like the English w, as is clear from the testimony of Quintilian and of later grammarians.
In Northern French and in Italian it has become the labio-dental v, and from French English has adopted this value for it.
His name is especially connected with the first description of locomotor ataxy, progressive muscular atrophy, pseudo-hypertrophic paralysis, glosso-labio laryngeal paralysis and other nervous troubles.