First, meter measures units of rhythmic repetition within a verse (line) of poetry.These metrical units are called feet. The standard meters are: Dimeter, two feet; Trimeter, three feet; Tetrameter, four feet; Pentameter, five feet; Hexameter, six feet; Heptameter, seven feet; and Octameter, eight feet.
Rhythm options in the English language, which are based upon syllabic accent, are the rhythms of: imab, trochee, anapest, dactyl, spondee, and pyrrhic. Iambs have one unaccented syllable followed by one accented syllable (per^ suade'). Trochees have one accented syllable followed by one unaccented syllable (par' don^). Anapest is like iamb but has two unaccented syllables in front of one accented syllable (of^ the^ joy'). Dactyl is the reverse of anapest with one accented syllable followed by two unaccented syllables (func' tion^ al^). Spondee has two twin accented syllables (hip' hop'). Pyrrhic has two twin unaccented syllables (of^ a^), which is problematic for writing. Spondees can be worked with, "Old court, / New love. / Fall down. / Left. Gone," but pyrrhics are harder.
So rising meter refers to metrical units, which are called feet, with rhythms that rise from unaccented to accented syllables. Iambs and anapests are therefore the rhythms in rising meters, with the meter itself being anything from dimeter to octameter. "A^ chance' re^ treat' " is a rising meter in dimeter.
Falling meter refers to metrical units, feet, with rhythms that fall from accented to unaccented syllables. Trochees and dactyls are therefore the rhythms in falling meters, with the meter itself again being anything from dimeter to octameter. "Just'-ice^ calls' to^ hon'-est^ work'-ers^" is a falling meter in tetrameter. Spondee and pyrrhic rhythms do not qualify for rising or falling meters.
Even though the rise and fall occur in the rhythm, the standard literary terms are "rising meter" and "falling meter," which is how you'll find them referenced in a literary glossary like Bedford St. Martin - Meyer Literature Glossary of Literary Terms. This is because the rhythm is assumed within the meter and because, once the rhythm is identified, it is the meter that governs the movement of the verses (lines) of the poem. Therefore it may be stated that the rising or falling meter identifies the rhythmic movement of the accented and unaccented syllables within the metrical feet, thus producing the terms rising meter and falling meter.
One of the most important features of the English language is that it is 'accented,' that is, there is a regular alternation of stressed and unstressed syllables in polysyllabic words. Accent or stress indicates that, that particular syllable is pronounced with more effort than the other syllable or syllables and is heard more loudly than the other syllable or syllables. The unaccented or unstressed syllable is pronounced with relatively less effort and is also consequently heard less loudly than the stressed or accented syllable.
The regular alternation between stressed and unstressed syllables produces the characteristic rhythm which is exploited by all poets.
1. The Rising Rhythm: is also known as the iambic or anapestic rhythm.
In the iambic rhythm every second syllable is stressed or unaccented Eg:
x / x / x / x / x /
To swell the gourd and plump the hazel shells.
Meter refers to the length of the line. It comprises either two or three feet. Since the above line has ten syllables with five regular accents it is scanned as iambic pentameter.
In the anapestic rhythm two unstressed syllables are followed by one stressed syllable. Eg:
x x / x x / x x /
I am out of humanity's reach.
In this line three syllables have been grouped as one foot. So, this line is scanned as anapestic trimeter.
2. The Falling Rhythm: is the reversal of the rising rhythm. It is known as the trochaic or dactylic rhythm.
In the trochaic rhythm every second syllable is unstressed or unaccented. Eg.
/ x / x / x / x
Peter Peter pumpkin eater
Since there are four feet this line is scanned as trochaic tetrameter.
In the dactylic rhythm the first syllable is stressed and the next two syllables are unstressed. Eg:
/ x x / x x
Half a league half a league.
Since there are two tri-syllabic feet, this line is scanned as trochaic di-meter.