when suddenly Snap, their dog, gave a savage growl. It was the kind of
growl he never gave unless he happened to be angry, and Bert knew, right
away, something must be wrong.

"What is it, Snap? A tramp?" asked the boy, looking around. Often Snap
would growl this way at tramps who might happen to come into the yard.
Now there may be good tramps, as well as bad ones, but Snap never
stopped to find out which was which. He just growled, and if that didn't
scare away the tramp then Snap ran at him. And no tramp ever stood after
that. He just ran away.

But now neither Bert nor Nan could see any tramp, either in the yard or
in the street in front of the house. Snap, though, kept on growling deep
down in his throat, and then, suddenly, the children saw what the matter
was. A big dog was digging a hole under the fence to get into the
Bobbsey yard. The gate was closed, and though the dog might have jumped
the fence, he didn't. He was digging a hole underneath. And Snap saw
him. That's why Snap growled.

"Oh, Bert! Look!" cried Nan.

As she spoke the dog managed to get through the hole he had dug, and
into the Bobbsey yard he popped. But he did not stay there long. Before
he could run toward Bert and Nan, if, indeed, he had that notion, Snap
had leaped toward the unwelcome visitor.

Snap growled and barked in such a brave, bold way that the other dog
gave one long howl, and then back through the hole he wiggled his way,
faster than he had come in. But fast as he wiggled out, he was not quick
enough, for Snap nipped the end of the big dog's tail and there was