"There's some sort of machinery in here," Peter explained. "Something to do with sluices and the amount of water that runs down the pipe line. Here the water is about ten feet deep. Can you all swim?"

David nodded emphatically and the twins doubtfully,

"Practically," said Dickie.

"I can do the sprawl," said Mary.

"Crawl, we mean," said her twin hurriedly,,

"Farther up here," Peter went on, "I've got a little secret hiding place and a lovely bathing beach, I'll show you. Come on."

She led the way through the heather to a snug little hollow which was so well hidden that Mary, talking as usual over her shoulder to Dickie, fell in with a smothered shout of alarm. When she had picked herself up, the others were laughing down at her.

"There are lots of these hidden little dells on the mountain," Peter explained.

Then she showed them the way in and how she could stand upright without being seen. The sun was hot and they were sheltered from the wind. They sat down and David began to feel sleepy.

"You'll come swimming with me one day, David?" Peter was asking, and he had to rouse himself to answer her. Then she nudged him and grinned.

"Babes in the wood," she whispered.

On the other side of the dell the twins lay stretched on the short grass fast asleep. Macbeth slept too, with his black head on Mary's chest.

3. The Mountain

From far away David heard Peter say, "Come on, you lazy lubbers! Time we were on the move."

He sat up with a start. "Have I been to sleep?"

"You have," Peter laughed. "I couldn't stay quiet any longer... Do you think the little ones are too tired to go on?"

The twins sat up.

"Too tired?" said Dickie, indignantly, "Course we're not too tired."

Macbeth yawned prodigiously and stretched his silly little legs. Then he looked up at Mary, with his head on one side, and wagged his tail as Peter led them out of the hollow.

She showed them her bathing beach, and then the track led them along the side of the reservoir. After a little the ground became soft again and they had to tread very carefully. At the head of the reservoir they crossed two streams, but although they were still climbing they could not, as Mary said, "see over the top" yet.

They were marooned now in a sea of heather. Only when they looked behind did they realize how far and high they had climbed. There were no gutters now, no inkling of hidden water, only sun, sky and brown heather.

"I feel about as big as a fly up here," said Dickie suddenly. "A King fly, of course," he added.

"A few more minutes," said Peter, "and you'll be up and almost able to see the other side over the edge."