How were bofur and bomb our rescued from smug?

Ropes were lowered to save the two dwarves.

"We cannot leave them. Get inside Mr. Baggins and Balin, and you two Fili and Kili-the dragon shan't have all of us. Now you others, where are the ropes? Be quick!" Those were perhaps the worst moments they had been through yet. The horrible sounds of Smaug's anger were echoing in the stony hollows far above; at any moment he might come blazing down or fly whirling round and find them there, near the perilous cliff's edge hauling madly on the ropes. Up came Bofur, and still all was safe. Up came Bombur, puffing and blowing while the ropes creaked, and still all was safe.