Daisy was more eager than he; she wanted very much to have a trilobite for her own keeping; the difficulty was, she did not know how to look for it.
All she could do was to follow her friend and watch all his doings and direct him to new spots in the mountain that he had not tried.

In the course of this business the Captain did some adventurous climbing; it would have distressed Daisy if she had not been so intent upon his object; but as it was she strained her little head back to look at him, where he picked his way along at a precipitous height above her, sometimes holding to a bramble or sapling, and sometimes depending on his own good footing and muscular agility.

In this way of progress, while making good his passage from one place to another, the Captain's foot in leaping struck upon a loosely poised stone or fragment of rock.
It rolled from under him.

A spring saved the Captain, but the huge stone once set a going continued its way down the hill.
"Daisy--look out!" he shouted.
"Have you got one ?" said Daisy, springing forward.

She misunderstood his warning; and her bound brought her exactly under the rolling stone.