One o’clock in the morning is a creepy time, even if the moon is shining, and it’s a good sight more creepy when you know something has happened. I hurried up to walk beside Mark because it was lonesome behind. He was heading straight for his house.

“Is it gone?” I asked. “Are you sure?”

“The padlock’s pried off, and the turbine ain’t in the shed.”

“How’d you come to find out about it at this time of night?”

“They waked me up. I ran to the window just in time to see ’em drive off l-l-licketty split. Then I went down, and the turbine was gone.”

“And then you came after me.” I was kind of tickled to think he did that. It showed he depended on me like and thought I’d stick by him and help out. “Did you see who it was?”

“No.”

“Which way did they drive?”

He jerked his thumb down the street. “No tellin’ which way they went. Prob’ly turned the corner; I don’t know which way.”

He went around through his yard to the workshop, and, sure enough, the padlocks had been pried off and Mr. Tidd’s engine was gone. I didn’t quite realize it till then, and I tell you it struck me all in a heap. There was Mr. Tidd off in Detroit, seeing about his patent and confident of getting rich, and here we were, left to look after the engine, and we’d let it get away from us.

“Maybe he can get his patent anyhow,” I said; but there wasn’t much comfort in that, for Mark explained that it couldn’t be done. His father had to have a model that would work, or no patent would be given to him. He was sure that Henry C. Batten was at the bottom of it all, and so was I.

“What they’re goin’ to do,” he said, “is to take dad’s turbine and make drawin’s from it. They’ll git another model made and smouge the patent before we kin b-begin to put a new one together.”

“They won’t dare take it to the depot and send it on the train,” I told him.

“Not from here. Maybe they’ll drive to some town near by and p-put it in a box and send it that way.”

“Maybe,” I says; but somehow I didn’t think so. Neither did Mark, I guess.

“Let’s see if we kin follow the wagon tracks,” he said, and got a lantern out of the shop.

It wouldn’t be so hard to do at that time of the night, because there weren’t any other wagons driving around, and the wheels of this one would be the last wherever it went. Besides, it had rained a little earlier in the night, and the dust in the roads was pasty.

We followed the tracks down the alley a couple of blocks; then they turned, and Mark muttered that he thought so.

“Thought what?” I said.

“That they’d turn this way—toward the river.”

“Why?”

“Because,” he said, “that’s where the Willis farm is.”

He told me as we walked along what he’d reasoned out. From the minute the turbine had been taken he began thinking and thinking the way he always does and putting two and two together. At last he got it into his head that he knew where the men were taking his father’s engine. First, there was Henry C. Batten driving on the road toward the Willis farm; second, Willis was the father to the engineer who had sneaked Batten in to see if the turbine worked; third, old Mr. Willis acted more skittish than ordinary when we came around, and, says Mark, that showed he had a guilty conscience; and last, and what Mark called the clincher of the whole thing, was that room in the farmhouse all fixed up with drawing-tools and tables just waiting for somebody to come in and set to work. I thought it over, and it looked to me as though he’d argued it out pretty straight.

“I guess,” I says, “the place to look for the engine is out at Willis’s.”

We followed the wagon tracks quite a ways farther just to make sure, and then turned back for home. It was beginning to get kind of pink in the east when I scrambled up to my room again and rolled into bed. I’d promised Mark to meet him early in the morning to see what we’d do.

I went over to his house right after breakfast, and he was at the gate waiting for me. “Careful what you say,” he told me. “Mother don’t know, and there ain’t no use frightenin’ her yet.”

“All right,” I says; “now what’s your scheme.”

“We can’t do nothin’ till we know where the turbine is and who t-t-took it. We think we know, but we got to make sure.”

“Let’s git at it, then,” I says. “What’ll we do—walk? It’s five miles.”

“I don’t want Binney and Plunk along—there’d be too many of us, and we might get caught, so we can’t git Binney’s horse.”

All of a sudden an idea hit me. The river ran right by the Willis house, and I owned a kind of a boat, flat-bottomed, but not very heavy. It was one of the kind that sort of skims over the top of the water without setting down into it much, and it was easy to row.

“What’s the matter with my boat?” I says.

“Say, that’s the very thing.”

“And I got two pairs of oars,” I told him, and most laughed out loud. Marcus Aurelius Fortunatus Tidd never cared much about exerting himself to speak of, and the idea of rowing a boat five or six miles wasn’t one he cottoned to worth a cent. He was sorry about the other pair of oars, and he showed it; but he didn’t say anything, and I knew he’d row the best he knew how when he got in the boat. If he had to work he’d work, and there wouldn’t be any soldiering. If he could get somebody else, by some scheme or other, to do his work for him he’d be tickled to death, but just to come out and loaf like some fellows do—well, he wouldn’t do it.

I kept my old boat above the dam tied up to a stake back of my uncle’s sawmill, and in ten minutes we had pushed her out into the river and were pulling up-stream, taking it easy so as not to tire ourselves all out at the start. It took us half an hour to get to Brigg’s Island. Above that the current got swifter, and we were quite a spell getting to the little island across from our cave. We went up the outside branch because the water was so shallow on our side, but we could see a little smoke going up from the place where the cave was, so we knew Sammy was home again. It’s lucky he was.

We rowed a little farther and then pushed in to the bank to rest a bit.

“We want to land a little this side of Willis’s,” Mark decided, “and s-s-sneak up same as we did the other day along the fence.”

“’Tain’t likely they’d hurt us.”

“I dunno. Never can tell when men are doin’ things like this. But I wasn’t figgerin’ on gittin’ hurt, only on bein’ seen. If they found somebody was s-s-spyin’ on ’em they’d up and s-s-scoot. Specially if Batten was to see me. I ain’t easy to forgit.” Mark grinned when he said that. He was right, though; Batten might not remember me if he did see me prowling around, and he might think I was just a kid playing some game or hunting or something; but if he caught sight of Mark, why, he’d know who it was in a minute and why he was there.

When we were rested up we got into my boat again and up the river we went. We rowed and rowed and rowed. “Thank goodness,” I said, “it won’t be such hard pullin’ comin’ back. We kin float down with the current.”

In about another hour we came to the island in the bend of the river, a quarter of a mile below Willis’s. Here the river ran through a big marsh that stretched, all green with tall water-grasses and cat-tails, on either side, and there wasn’t a good place to land. We didn’t want to have to wallow through the marsh, because we knew we’d get in mire up to our knees and maybe higher, and because it looked just like the kind of a place where rattlesnakes would be fussing around. In general, I’m not afraid of rattlesnakes, but I don’t like to go plunging through a place like that and maybe stepping right on one before he has a chance to rattle at you.

Back among the reeds and grasses we could see lots of muskrat houses, and we stowed that fact away to remember, because you can make pretty good money trapping rats and selling their skins; and I thought it would be a fine place for wild duck in the early spring.

We turned back a little to where the shore was more solid and found a place where a rail fence ran right down to the water. We made for that and tied the boat. It wasn’t much of a trick to clamber along the rails to shore, though Mark made them bend so I thought it wouldn’t be very surprising if they broke. That fence wasn’t built to hold fat boys, but to keep in cows.

There was a bank maybe ten feet high to climb before we got to the road. We looked up and down pretty careful before we got up in sight; but nobody was coming, so we ducked cross to the north side where there were a lot of hazel bushes growing along the roadside, and some blackberry bushes, as we discovered by the prickers when we pushed our way through them.

We were pretty cautious, keeping back in the bushes and ready to lie down out of sight if anybody came along, but nobody did, an............