"Whew! Well, what do you think of that!" gasped Joe.
"I thought the whole mountainside was coming away," exclaimed Ding-dong, startled into plain speech by his alarm.
Of course the first thing to be done was to clamber out of the car and examine the monster rock, which had come to rest some distance up the side of the opposite cliff to that from which it had fallen, such had been its velocity. Nat could not help shuddering as he realized that if the great stone had ever struck the auto it would have been, in the language of Cal, "Good-night" for the occupants of that vehicle.
"Ach, vee vould haf been more flat as a pretzel alretty yet," exclaimed Herr Muller, unslinging his ever ready camera, and preparing to take a photo of the peril which had so narrowly missed them.
"This must be our lucky day," put in Joe, "three narrow escapes, one after the other. I wonder if there'll be a fourth."
"Better not talk about it, Joe," urged Cal, "the next time we might not be so fortunate."
"Guess that's right," said Nat, who was examining the boulder with some care.
Apparently it had been one of those monster rocks which glacial action in the bygone ages has left stranded, delicately balanced on a mountainside. Some rocks of this character it takes but a light shove to dislodge. So perfectly are other great masses poised that it takes powerful leverage to overcome their inertia—to use a term in physics.
But the scientific aspect of the rock was not what interested Nat. What he wanted to find out was just how such a big stone could have become unseated from the mountainside and at a time when its downfall would, but for their alertness, have meant disaster and perhaps death, to the Motor Rangers. Nat had an idea, but he did not wish to announce it till he was sure.