They were to hold each other's hands tightly and keep together.
Frequent flashes of lightning revealed the woods in a tremendous state of agitation and it seemed better to be moving than to stand still and watch the terrifying spectacle.
On they stumbled, but suddenly came to grief, for the four in front fell headlong over a tree that had been blown across the path, and the other five hearing their cries of warning too late, followed after.
By the time they had picked themselves up the storm had grown so furious that they could only press miserably together and wait for it to pass.
Suddenly Tom amazed them all by putting his hands to his mouth and blowing a strange kind of hollow whistle that sounded like the note of a trumpet.
He repeated the whistle again and again.

"You may not believe it," he said between calls, "but the hunter who taught me this, told me never to use it unless I was in dire need.

Then help of some sort would surely come.

It is called the Elf's Horn." "Did you ever try it before," asked Reddy curiously.
"No," he answered, "I never did.

I suppose it's only superstition, but I love hunter's lore.