Metrical prose in Charles Dicken's "Martin Chuzzlewit"

At the beginning of the next-to-last chapter of Charles Dickens's "Martin Chuzzlewit", when John Westlock and Ruth Pinch begin the walk when he'll propose to her, the prose slips into an iambic metrical pattern, with alternating heptameter and pentameter phrases and a concluding tetrameter: "Brilliantly the Temple Fountain sparkled in the sun, and laughingly its liquid music played, and merrily the idle drops of water danced and danced, and peeping out in sport among the trees, plunged lightly down to hide themselves." The narrative left little doubt about the imminent marriage proposal, but the meter combines with the "brilliant" adverbs that begin the first three phrases to celebrate it in advance. (Andrew Shields, #111words, 28 June 2021)

"John Westlock and Ruth Pinch", Sol Eytinge, Jr., wood-engraving 1867