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