"But it may be dangerous!"
"It will be more dangerous to stand still! Don't you know that a moving body has a better chance over thin ice than one standing still? Keep going, Mollie, and head for shore!"
"Oh, I'm sure something is going to happen!" cried Amy.
"Nonsense, be quiet!" urged Betty. "Grace, give her a chocolate! Mollie, lower that wheel again."
Again the "propeller" engaged the ice, and the Spider forged ahead. Grace looked back, and saw where a big crack had appeared. It was constantly widening.
Then came a thunderous report. The girls screamed, and Betty almost let go of the tiller. Then she grasped it more tightly, for she saw, with a shudder of fear, that black water was now all around them.
"Stop! Stop!" cried Betty to Mollie. "Stop the boat! We're on a big cake of ice and we're floating away! Stop it!"
In an instant Mollie had lifted the wheel, and in the next she had shut of the motor. The Spider with the girl passengers was indeed marooned on an immense cake of ice, while all about were other cakes, grinding and smashing over one another. The river was breaking up fast.