0 in poetry, a foot (= a unit of division of rhythm) with one strong or long syllable followed by two unstressed (= not strong) or short syllables:
We can hear his voice sounding out the dactyls of "half a league, half a league onwards".
The very name of Anna Karenina has a galloping rhythm, dactyls being commonly used for hoofbeats.
The dactyls in line 114 contribute to the urgent, questioning tone.