"Why don't they stop?" wailed Grace. "Then we wouldn't bump them so
hard!"

As if in answer, there came echoing over the dark water the clang of
the engine-room bell, that told half-speed ahead had been ordered. A
moment later came the signal to stop the engines.

"Oh, if only Uncle Amos-- or some of the boys-- were here!" breathed
Betty. "Girls, try once more!"

Together Mollie and Grace whirled the crank, and an instant later the
motor started with a throb that shook the boat from stem to stern.

"There!" cried Betty. "Now I can avoid them."

She threw in the clutch, and as the Gem shot ahead she whistled to
indicate her course. This time came the proper response, and a little
later the motor boat shot past the towering sides of the river
steamer. So near had a collision been that the girls could hear the
complaining voice of the pilot of the large craft.

"What's the matter with you fellows?" the man cried, as he looked down
on the girls. "Don't you know what you're doing?" Clearly he was
angry.

"We got adrift, and the motor wouldn't start," cried Betty, in shrill
tones.

"Pilot biscuit and puppy cakes!" cried the man. "It's a bunch of
girls! No wonder they didn't know what to do!"