But meanwhile the treacherous mist was rolling up thicker and thicker. The girls hurried back as fast as they could, but this time they missed the cross altogether. There is nothing so easy as to get lost in a fog on the moors. Thoroughly frightened, they called to Uncle David, but they could hear nothing in reply. They wandered on, hoping he would sound the hooter and so give them some clue to his whereabouts, but everything was deadly still. It seemed as if a great white wall had arisen and shut them up in some elfin castle on the moor.
"We're pixie-led. That's just all about it," said Merle. "I told you it was an unlucky day."
"Well, look here, we mustn't go too far! If we walk on like this we may be going straight away from the road, and might tramp miles or get into a bog. We'd better stay where we are and shout every now and then, and perhaps Uncle David will find us."
Two very forlorn girls, feeling extremely chilly and cold in the clammy fog, squatted down on the heather and took it in turns to call "Coo-e-ee!"
"What are we to do if we have to stop here all night?" asked Merle, nearly crying.
"I don't know!"
"How long do these mists last?"
"Oh, days and days sometimes I suppose!"
"Should we be dead before morning?"
"Oh, I hope not! Shout again!"