From Hreinn Benediktson´s edition and commentary on the First
Grammatical Treatise (part 2):

'In the third section (85:28-86:18) the FG establishes the quantity
correlation by producing a list of eighteen pairs, followed by
illustrative sentences, one for each of the nine oral and nine nasal
vowels previously established, and each distinguishing, by means of
the superscript accent mark, a long vowel from the corresponding
short one. These eighteen pairs are as follows:

(Note: nasal vowels are placed within paranthesis)

far 'vessel': fár 'harm'
r(a)mr 'mighty': r(á)mr 'harsh-voiced'
ol (hooked o) 'ale': ól (hooked o) 'strap'
u(o)n (hooked o) 'accustomed'(fem.): u(ó)n (hooked o) 'prospect'
se þo 'look thou': séþo '(they) nailed'
fr(a)m(e)r 'brazen' (masc.pl.): fr(a) m(é)r 'from me'
uer (hooked e) 'husband'(acc.): uér (hooked e) 'fond'(fem.)
u(e)nesc (hooked e) 'get into (this) habit'(subj.): u(é)esc (hooked
e) '(he) is confident of'
uil 'wilfulness': uíl 'misery'
m(i)nna 'to remind': m(í)nna 'my'(gen.pl.)
goþ 'God': góþ 'good'(fem.)
m(o)na 'will not': m(ó)na 'mother'
Goþröþe (proper name, dat.)(short ö): góþ röþe (long ö) 'good oars'
mönde 'would': mönde (long ö) 'ridged' (subj.)
dura 'door' (gen.pl.): dúra 'to doze'
r(u)nar 'boars': r(ú)nar 'runes'
flytr '(he) drives: flýtr '(it) floats'
br(y)nna 'to water': br(ý)nna 'sharper' (masc.acc.sg.)

5.2.2.2. Comparison with Other Sources of Evidence

'In order to assess the value of this evidence, in the same way as
in cht.5.2.1.2, the FG's statements have to be examined in the light
of other available evidence. The following points, escecially, call
for remarks:

5.2.2.2a The Nasality Correlation: NASAL VS. NONNASAL

'Unlike most of his other statements, the FG's information about the
existence of nasal vowels in Old Icelandic was, in former times,
often regarded with considerable doubt, and even wholly discredited;
thus, the FGT has been said to contain 'imaginary nasal vowels',
which, for the most part, 'have nothing to do with real nasality',
having 'no firm root in the language', but rather being 'no doubt
the exclusive product of the author himself'. This view was based on
the fact that vocalic nasality is attested nowhere else in Old
Icelandic tradition: nasal vowels are not represented by separate
symbols in the orthography, not even in its earliest stage; and in
the rhymes of scaldic poetry (as well as in alliteration and in the
rhythmical patterns of the verse line) no distinction of this kind
is made. Thus, the two principal sources of contemporaneous evidence
fail to verify the FG´s statements, and so there remains only the
third source, viz., comparative evidence. And even this source, in
part, fails to support the FG´s statements, for in later Icelandic
there are no traces of distinctive vocalic nasality.

'However, it should be noted that the pther sources do not
contradict the FG's testimony; they only fail to give explicit
support to his statements. Therefore, if we assume that his
information is trustworthy, we may readily explain the failure of
the other sources to confirm it. Thus, the absence of an
orthographic representation of vocalic nasality might be due either
to its disappearane as early as the twelfth century (at least in
those varieties of Icelandic that are represented by the very few
manuscripts that happen to be preserved) or simply to the lack of an
appropriate symbol in the Latin script (cf.also the absence of an
orthographic representation of vocalic quantity in the earliest
writing; see cht.5.2.2.2f below).

'Similarly, the reason for the failure of scaldic rhymes to
distinguish nasal and oral vowels might be the same as caused 'a'
and 'o' (Note: hooked 'o') to be treated as one metrical unit (see
cht5.2.1.2c above); as we shall see (cht.5.2.2.2c), the same
function trait in fact characterized the nasal- vs. oral-vowel
distinction as well, and there is therefore every reason to believe
that the metrical function of these vowels was affected in the same
way.

'Thus, even though these sources, alone and by themselves, fail to
confirm the existence of the nasal-vowel distinction, they cannot
serve to disprove it. The FG's credibility, on this point, therefore
depends on the only remaining evidence, which is the comparative
data, or rather part of it, viz., the prehistoric data as obtained,
mainly, by comparison with related languages. And this evidence,
marginal as it may be, not only does not disprove the FG's
statements, but on the contrary lends them overwhelmingly convincing
support. Thus, from this evidence it appears (a) that in all those
forms in which the FG claims nasal vowels, the vowel was followed
(or preceded) by a nasal consonant in Proto-Nordic (or Proto-
Germanic), and (b) that in those forms that are said to have an oral
vowel, this was never followed (or preceded) by such a consonant.'

End of quotation.

As can be see from the above quotations, the subject of nasality is
not one that we modern West-Norse have an easy time with. It is for
this reason, and for clarity of script, that I advocated in one of
my posts on the 'vowel-system' that the vowels for Old West Norse
(in the FG's day and earlier, including classical poetry) be shown
as follows:

i, í
y, ý
u, ú
a, á
e, é
o, ó
æ, ´æ (accent on top)
ao, aó (written as a single letter)
oe, oé (written as a single letter)

As the FG points out:

æ = a+e (the short was sometimes written hooked e, sometimes æ)
ao = a+o (which was sometimes written as hooked o, sometimes ao)
oe = o+e (which was sometimes written as hooked o, sometimes oe)

The modern conventions of printing hooked 'o' for the short of 'oe'
and hooked 'e' for the short of 'æ' are purely conventional. Long
'ao' (aós = god) does not become 'á' in Icelandic until after the
FG's time. Adopting the vowel-scheme shown above has several major
advantages for learning and reading Old Norse from the FG's time or
earlier: 1) it graphically represents 'æ' 'oe' and 'ao' in a way
that is consistent with their true origins (thus facilitating the
learning and pronounciation of these sounds) 2) it is consistent in
that in no case is the long and short of the same vowel represented
by two different letters (thus helping to eliminate some of the
confusion experienced by those learning Old Norse) 3) it frees up
the symbol 'lined o' for use in representing 'ö2' (a different sound
altogether from 'ö1' above)(Note: FG does not mention 'ö2', which is
so rare that I am not even sure if it actually occurs as a long
vowel or has a nasal equivalent, despite the fact that it occurs in
a few very common words) 4) it has no hooks or other markings under
the letter (thus providing space for indicating nasals below by the
addition of a hook or a dot). This last point is very important, as
placing dots OVER letters with accents is visually confusing and
requires that accents be moved to make room for dots. Secondly, it
is much clearer to show only lengthing above and nasalization below.
This system would be more 'user-friendly' (to quote Microsoft). One
could print text with or without nasal-markings below the letters.

Please let me know your thoughts about this topic.

The etymologies for the FG's examples will be in my next post.

Regards,
Konrad