Nothing in this short poem quite adds up, and that seems to be the point. A group of men haul a galley, a seagoing ship, through a gully, apparently meaning to reach the sea. Then they give up the idea and row along the shore instead. The picture is slightly absurd: a boat meant for open water dragged through a dry ditch, then settling for something smaller.
The last lines shift the scene again. Judges sit on benches, and "going all afternoon in the garden" could mean the benches are rowing seats, or that a court is in session outdoors. The poem doesn't settle it, and the images blur together like a half-remembered dream.
The speaker seems calm and amused. "It was pleasant to see" sets a relaxed, watching tone. The mood is drowsy and gently comic, with no urgency. Ambitions shrink, the journey stays close to land, and the poem seems content to let an afternoon drift by.