What is the Extended metaphor to dickinsons i like see it lap miles?

The extended metaphor in Dickinson's "I Like to See It Lap the Miles" is that of a bird in flight. The poem compares the movement of the train to the graceful and effortless flight of a bird, using words like "lap," "soar," and "wings." The train's journey is likened to the bird's migration, a symbol of freedom and the pursuit of distant goals.