Several times he was on the point of letting go and dropping further down, but he dreaded some mistake which would draw attention to the spot. If he should try to swim under the surface, he might be forced to come up too soon, or might strike some obstruction in the stream that would fling him over as though he was a porpoise. It was the fear of a catastrophe of this nature which held him where he was, while he peered through the shrubbery like some wild animal glaring out from his covert upon his enemies.