Following is the text of a posting to alt.usage.english 2005 Jan 28:
Some remarks from different posters in recent days suggest
that it's time to discuss again the conflict between two
different meanings of "long" and of "short".
When we were in elementary school, the teacher taught us
that the "a" in "rake" was "long a" and the "a" in "rack"
was short "a". And the vowels in "peek", "pike", "poke",
"root" were long while the vowels in "peck", "pick", "pock",
and "rut" were short.
There is another meaning for each of "short vowel" and "long
vowel", and it's the one phoneticians are most likely to
have in mind when they use those terms. That is, a short
vowel is one whose duration is short, and a long vowel is
one whose duration is long. That is the meaning of "long"
and "short" that corresponds to the presence or absence of a
colon after a vowel in the International Phonetic Alphabet.
I've read that there is a connection between the two
concepts, in that the vowels that are now referred to by
elementary school teachers as "long" and "short" were indeed
long or short in duration when the words were applied to
them. In modern English, the vowel in "peek" may be
pronounced with relatively long duration or relatively short
duration, but it's still a high front vowel. And the vowel
in "pick" may be pronounced with either long or short
duration, but it's still a near-high, near-front vowel.
It would be good if everyone would avoid using the terms
"long vowel" and "short vowel" as we learned them in
elementary school, saving them to describe actual relative
duration.