Answer:
The figure of speech used in the given sentence is "personification."
Personification is a literary device where human qualities or actions are attributed to non-human entities or objects. In this case, the lullaby is personified by ascribing the human action of "hissing" and the non-human entity "water of pond" and "roaring steel river."
The lullaby is described as having the ability to produce sounds similar to the hissing of water in a pond and the roaring of a steel river.
By personifying the lullaby, the author creates a vivid and imaginative image, making the lullaby come to life and enhancing the sensory experience for the reader.
It adds a sense of movement and power to the lullaby, transforming it from a simple sound into a more dynamic and evocative element.
Hope this helps!