But these were few.
The rock was like smooth red iron.

Slone had never seen such hard rock.
It took him long to realize that it was marble.

His heart seemed a tense, painful knot in his breast, as if it could not beat, holding back in the strained suspense.

But Nagger never jerked on the bridle.
He never faltered.

Many times he slipped, often with both front feet, but never with all four feet.