Temeraire bobbed his head once and pulled the boulder upright with a little effort. It was not terribly heavy, to his mind, but it was bulkier than he had thought it would be, and he wobbled a little and put out a wing for balance as he hefted it in his claws.

The boulder described an impressive parabola through the air when he threw it, grunting slightly with the effort, but in the end, it, too, only struck the invisible wall and rolled back toward him, sending up a brief cloud of dirt and grass as it landed.

"I do not suppose there is very much to observe," he said sourly, "only that a larger rock has much the same effect. Do you know any spells of note?"