The Hobbit
The Hobbit, Chapter 12
How does Smaug make the rock-shadows dance?
How does Smaug make the rock-shadows dance?
Smaug makes the rock-shadows dance with his "hot breath" (fire).
"Smaug came hurtling in from the North, licking the mountain-sides with flame, beating his great wings with a noise like a roaring wind. His hot breath shrivelled the grass before the door, and drove in through the crack they had left and scorched them as they hid. Flickering fires leaped up and black rock-shadows danced. The darkness fell as he passed again."
The Hobbit, Chapter 12