Ossaroo was himself well aware of the circumstance--and more troubled at it than any of them--for it rendered it more difficult for him to preserve his equilibrium.

Caspar at length also observed the trembling of the rock, but it gave him no particular uneasiness: as, after what had passed, he felt confident that Ossaroo would be able to keep his place.

Nor was it the fear of his falling in that way that was distressing the young botanist; but rather a deduction which he drew from the circumstance, not apparent to the less philosophic mind of his brother.
The shaking of the rock had suggested to Karl a dangerous contingency.
What was it?
The speech addressed by him at that moment to Caspar will explain.
"Oh, brother!" he exclaimed, on perceiving the danger, "if the rock should fall--" "No danger of that," said Caspar, interrupting him; "it stands firm enough.

True, I see it shake a little, but only a very little; and that only when the brute springs up against it.

No danger, I should think!" "But I fear there is clanger," rejoined Karl, in a tone of undiminished anxiety.