On the Dundale Road a motor-car was drawn up .... and the motorists were resting on the scorched, drab grass. After some ten minutes, Dick saw a wisp of smoke from where the motor-car was, along the Dundale Road. Some muttonhead visitors been chucking matches about says Nancy; John and Nancy race down and put out the fire (PP17).
Later, before Dick is leaving on his mission to Beckfoot to test the sample of gold, he hears a motor-car hooting through the woods and along the Dundale Road its noise stopped. Another of those picnic parties supposed Dick. The motor-car leaves, and the visitors who had rested there, eaten their sandwitches by the roadside and admired the view over the hills were already a dozen miles away. A thin wisp of blue smoke curled in the grass where they had been. No one saw it. This time there were no watchers on the Great Wall (PP30).