I listened, and heard a regular, hollow, booming sound, something like the very distant discharge of cannon.

“It’s the horses walking on the ground-always sounds that way in the night,” I answered.

Again I was almost asleep when Ollie took hold of my arm, and said, “What’s that?”

[Illustration:  Effect of a Strange Noise]

I once more listened, and recognized a peculiar creaking noise as that made by the horses cropping off the grass.  I explained to Ollie, and then dropped off sound asleep.  I don’t know how long it was, but after some time I was again roused up by a nervous shake.

“Listen to that,” whispered Ollie.  “What can it be?”

I sat up cautiously and listened.  It was a strange, rattling, unearthly sound, which I could not account for any better than Ollie.

“It’s a bear,” he whispered.  “I heard them make that noise at the park back home.”

I was puzzled, and concluded that it must be some wild animal.  I took down one of the guns, crept softly to the front end of the wagon, raised the flap, and looked out.  The wind was still, and the night air met my face with a cool, damp feeling.  The moon had just risen and the lake was like silver.  I could see the horses lying asleep like dark mounds.  But the mysterious noise kept up, and even grew louder.  I grasped the gun firmly, and let myself cautiously out of the front end of the wagon.  Then I climbed back in less softly and hung up the gun.

“Wh-what is it?” asked Ollie, in a faint whisper.

“It’s your eloquent Uncle Jack snoring,” I said.  “He’s one of Grandpa Oldberry’s sim’lar varmints.”

III:  FROM LOOKOUT LAKE TO THE MISSOURI RIVER

Our first night in the Rattletrap passed without further incident—­that is, the greater part of it passed, though Ollie declared that it lacked a good deal of being all passed when we got up.  The chief reason for our early rise was Old Blacky, a member of our household (or perhaps wagonhold) not yet introduced in this history.  Old Blacky was the mate of Old Browny, and the two made up our team of horses.  Old Browny was a very well-behaved, respectable old nag, extremely fond of quiet and oats.  He invariably slept all night, and usually much of the day; he was a fit companion for our dog.  It was the firm belief of all on board that Old Browny could sleep anywhere on a fairly level stretch of road without stopping.

But Old Blacky was another sort of beast.  He didn’t seem to require any sleep at all.  What Old Blacky wanted was food.  He loved to sit up all night and eat, and keep us awake.  He seldom even lay down at night, but would moon about the camp and blunder against things, fall over the wagon-tongue, and otherwise misbehave.  Sometimes when we camped where the grass was not just to his liking he would put his head into the wagon and help himself to a mouthful of bedquilt or a bite of pillow.  He was little but an appetite mounted on four legs, and next to food he loved a fight.  Besides the name of Old Blacky, we also knew him as the Blacksmith’s Pet; but this will have to be explained later on.