"Two vowels put side by side could indicate that the vowel sound
intended was represented by neither of them but signified a third
sound made in their vicinity: AI could thus signify Æ, AU could
signify O or Å. But this use of two vowel runes together could set a
further trap: were they to be read as a monothong (Æ,O) or a
diphthong (ÆI,ÅU)? The nasal Å-rune was given a notable special
function. On the big Jelling stone it signifies nasalized Å but it
is also used there for an Æ sound: såR = sæR. ('for himself'). And
one may also ask whether there was a special orthographic rule that
Å + U could represent the monothong O,Å: on the Nörre Nærå stone we
saw that 'niåut' must be read 'njót'; on the big Jelling stone
'þåurui' must be read as 'þorwi'; on the Stora Köpinge stone in
Skåne and on the Haddeby stone 2 'åuk' can no doubt only be read
as 'ok' (cf. the spelling 'aok' on the Tillitse stone); 'åumuta' on
the Sjörind stone must accordingly indicate a pronunciation 'åmunda',
which makes the name the same as the one on Århus stone 1; cf.
'åulaibr' in the Ballaugh inscription, Man (Ingrid Sanness Johnsen,
Stuttruner, p.226)." (Note: I will post something interesting about
the name 'åulaibr' later)
Notice what Moltke says about 'ok'. Now consider the following:
Short O does not occur in Proto-Norse except as the A-mutation of U,
which was already in operation throughout Scandinavia from the early
Proto-Norse period. The 'o' in 'ok' cannot be from Proto-Norse long
Ó, as 'ok' is neither written nor pronouced 'ók'. After A-mutation
of U had been operating for many centuries in Scandinavia, a new 16
letter fúþårk was introduced. In the earliest Danish and Swedish
inscriptions in the new fúþårk, two vowel runes (AU or ÅU) were used
to represent the short 'o' in 'ok' besides other sounds. Most people
living then were either illiterate or only marginally literate. 'ok'
was a very common word and could be seen on existing inscriptions.
When someone important died and a new stone had to be raised, the
existing spellings of 'ok' were simply tranfered to the new stone.
This is an fine example of conservative spelling. Even long after
the tradition of representing O by U had become firmly entrenched in
most areas, spellings like 'auk' and 'åuk' still appear regularly.
Eventually, the old conjugation gives in to the changing times and
begins to appear as 'uk'. Meanwhile, far off in an isolated part of
Norway, an anonymous inscriber 'at eggjum' spells the word 'uk'. He
could have spelled it 'ok' or 'ók', as he was far enough behind the
times to still be using the Óðal-rune throughout his inscription,
but he chose not to. He used the old-fashioned 'uk', which in time
would also become the new fashion in the south and east, displacing
the spellings 'auk' and 'åuk'. By his spelling, he told us something
about our linguistic history (especially for West Norse speakers):
the original grade of the vowel before 'k' in 'ok' was U, which was
mutated to O by a following A in the Proto-Norse period. '-uka' was
once used enclitically, often at the end of the compound it joined -
much as in Sanskrit. For example, one could say 'JohnPaulMaryuka'.
Nevertheless, the old spelling tradition was strong enough to make
it into a 13th century Icelandic copy of Hávamál. In verse 98 we
read: 'Auk nær apni skaltu, Óðinn, koma...'. We have all kinds of
evidence that in Iceland 'auk'(besides) was always 'auk' and 'ok'
was always 'ok' - so the tradition must have been a very strong one
indeed. If we want to write 'ok' in runes in such a way as to show
its origin, then we will use the spelling 'uk'.