Both poems are made up of regular quatrains of rhyming couplets, one based on iambic and one on trochaic metre.
The sense of listening to and "feeling" the motion of the locomotive is created by the rhythm (the trochaic regularity of "clanking, stumbling, down from Selston").
They proposed that children at the early stages of language attempt to produce minimal words, one form of which is a trochaic foot.
He describes the preference that some English-speaking children demonstrate for trochaic (strong-weak) patterns.
