What is the base meter of this poem?

On first looking into Chapman's Homer

Much have I travell'd in the realms of gold,

And many goodly states and kingdoms seen;

Round many western islands have I been

Which bards in fealty to Apollo hold.

Oft of one wide expanse had I been told [5]

That deep-brow'd Homer ruled as his demesne;

Yet did I never breathe its pure serene

Till I heard Chapman speak out loud and bold:

Then felt I like some watcher of the skies

When a new planet swims into his ken; [10]

Or like stout Cortez when with eagle eyes

He star'd at the Pacific-and all his men

Look'd at each other with a wild surmise-

Silent, upon a peak in Darien.

-John Keats

iambic pentameter

dactylic hexameter

anapestic tetrameter

Iambic pentameter.

Explanation:

Iambic Pentameter is the construction of lines in poetry with five iambs / metrical feet. These meter scheme is also called as pentameter, where an stressed syllable follows an unstressed syllable in all the lines.

"On First Looking Into Chapman's Homer" by John Keats is an Italian sonnet that has a perfect rhyme scheme of abbaabba for the first eight lines. the eighth line is the volta, from where the tone changes and the rhyme scheme also changes to cdcdcd.

This poem uses the iambic pentameter form of meter, whereby the lines contain ten syllables, an unstressed syllable followed by an unstressed syllable. Example-

Much have I travell'd in the realms of gold,

And many goodly states and kingdoms seen;

The stressed syllables are in bold, alternating in between unstressed syllables. Thus, the base form of the poem "On First Looking Into Chapman's Homer" is iambic pentameter.