ll and Frank were comparing notes. "It might have been more serious
only for that. It was because they set the trap that Amy was caught in."

"Oh, well then, I'm glad they did fight--with snowballs," returned Grace
in a different tone.

The big box had been unloaded in front of the cabin when the boys
arrived, and while Grace and Mollie went in to talk to Betty and Amy,
the boys proceeded to get out the motor.

As Will had said this was one taken from a motorcycle. It was of two
cylinders, and powerful. The boys planned to set it in the after part
of the cockpit of the ice boat, and take off the sail. The motor would
revolve a wheel at the stern, the wheel having spikes all around the
rim. These spikes would dig into the ice and thus send the boat ahead. A
lever was provided so that the spiked wheel could be pushed down lightly
or hard on the ice, thus regulating the speed of the queer looking
craft. The _Spider_ could be steered as before, by moving the rear
runner.

"Now we'll show you some sport!" cried Will, when he had seen that all
the parts of the motor were there. "We'll go some, now!"

But if the boys had hoped to try their new craft that day they were
disappointed, for there was more work about installing the motor than
they had calculated on. The girls grew tired of waiting, and strolled
over to the village, the day being pleasant. They met Mr. Blackford
coming from the depot, he having returned to complete his visit with the
boys.

He looked rather tired and discouraged, which prompted Betty to ask in a
low voice:

"Have you had any trace of your sister?"

"None at all," he said despondently. "I seem to be up against a stone
wall, and so do the lawyers and searchers I have engaged. We get to a
certain point, and there we stick. After that, all traces of her are
lost."

"Poor little sister! I wonder what she will look like, and what she will
be like?"

"Then you never saw her?"

"Only when she was a baby, and I a small chap. I do not remember her.
But I have not given up hope yet. Now, how are you all, and what has
happened since I went away?"

Betty told him, including the news about the new auto ice boat.

"That sounds interesting," declared Mr. Blackford. "I want a ride in
that."

"That's more than I do," spoke Mollie. "I'd rather go in an airship."

"So would I," agreed Grace.

But when the next day, after several false starts, and a breakdown, the
motor was finally set in motion on