How would you best describe the meter of the poem "A Psalm of Life" by Henry Longfellow?

Interesting question.  Longfellow, as a Romantic poet,
relies carefully on meter and rhyme schemes to present his moral-teaching poetry.  "A
Psalm of Life" is mainly trochaic tetrameter which means
that most of its lines have four sets of two-syllable pairings (feet); this is where the
word tetrameter comes in--to describe the four feet. Trochaic means that in each of
those parings or feet, the words have a stress on the first syllable and then an
unstressed syllable.  Below I've listed the first line of the poem and have italicized
the stressed portion of each
foot.

"Tell me
not in mournful
numbers,"

If you read this out loud,
its beat should sound like: Dum-da, Dum-da, Dum-da, Dum-da. I usually beat out the lines
of poetry on my desk to get a feel for what its rhythm should
be.

That being said, in each of Longfellow's four-line
stanzas, generally the second and fourth lines are missing half a foot or one beat--so
instead of having four feet total, those lines have three and a half.  This could be
Longfellow's clever portrayal of how life can cut off before you think it should be
finished, which would certainly illustrate the theme of "A Psalm of Life." Or, it could
simply be Longfellow's demonstrating his skill with handling meter and putting his own
spin on it.