ge sounds."

"There it is again!" I said, catching his arm, and unable to control
the feeling that at any moment something might spring out of the
darkness upon my back.

For the same curious rustling of leaves came whispering from among the
trees, and then there was a low expiration of breath, as if some great
beast had yawned.

Click-click, click-click sounded loudly on the night air, and I followed
the doctor's example, cocking both barrels of my piece.

"It's coming nearer, whatever it is," said the doctor in a low tone,
"and that strange noise means, I think, that it is some great serpent."

"But would serpents be out at night?" I said.

"That one was the other night, Joe, and we must not reckon upon the
regular habits of animals if we light great fires in their lairs."

We sat listening again, and the rustling sound began once more.

"It's just as if the thing were climbing along trees that are not strong
enough to bear it," I said in an excited whisper, "and they keep flying
up after it passes."

"Hush!" said the doctor.

We listened, and from out of the darkest part before us there arose a
loud tearing noise as if bark was being scratched from a tree trunk.

"Some kind of beast of the cat family, I should say," whispered the
doctor. "Pst! be ready; but don't fire unless we are attacked."

Just then there was a rush, a scramble, a dull thud, and some creature
uttered a sound that seemed like the word _Howl_ in a hollow echoing
tone.

Again and again there was the low rustling, and then that word _Howl_
that seemed to come from some great throat; and in imagination I saw in
the darkness a pair of fiery eyes and a set of great sharp teeth.

"Yes; some kind of cat, leopard, or panther," said the doctor; but, low
as his utterance was, it seemed to irritate the creature in our
neighbourhood, as it kept on the rustling, for there was a harsh
exclamation and the earth seemed to be torn up.

Then all at once the sound ceased, and it was perfectly still for quite
a quarter of an hour, which seemed an endless time; and then, tired of
staring intently into the darkness, and too much excited to be silent, I
whispered:

"This night-watching is the hardest part of our work, doctor."

"Oh! no, my boy. It makes you a little creepy at first, but as soon as
you feel your own power and how you must alarm these creatures, you will
get used to it."

"But the fire makes them see us, and we can't see them," I