from
The Collaborative International Dictionary of English v.0.48
Verner's law \Ver"ner's law\ (Philol.)
A statement, propounded by the Danish philologist Karl Verner
in 1875, which explains certain apparent exceptions to
Grimm's law by the original position of the accent. Primitive
Indo-European k, t, p, became first in Teutonic h, th, f, and
appear without further change in old Teutonic, if the accent
rested on the preceding syllable; but these sounds became
voiced and produced g, d, b, if the accent was originally on
a different syllable. Similarly s either remained unchanged,
or it became z and later r. Example: Skt. sapt[=a] (accent on
ultima), Gr. 'e`pta, Gothic sibun (seven). Examples in
English are dead by the side of death, to rise and to rear.
[Webster 1913 Suppl.]