A flat-bottomed boat that's used to carry wood. This act of "catching" the boat recalls Huck's catching of the canoe in Chapter VII, when he jumped out into the river while Pap wasn't looking. This parallel may be Twain's way of suggesting that Jim was planning to run away, just like Huck, and that Huck fits in more with the slaves, the lowest rank in society, than with prim and proper people like the Widow Douglas.
"because it was sent for a warning..."See in text(Chapter XV)
Twain uses Jim's interpretation of the "dream" as foreshadowing: the pair will meet a lot of quarrelsome folks, and they will get into a lot of trouble, but it remains to be seen whether or not they'll make it to the free states. At this point in the narrative, it's important for both the reader and Twain to know that what follows isn't just a random series of events taking place on a river and that this journey will eventually lead us somewhere. Where that is, we'll have to find out.
"So she'd had a rough time..."See in text(Chapter XV)
After the ordeal of trying to find the raft in the fog, it's understandable that Huck's irritated with Jim and the way he handled their separation that night. It's easy for him to think, because he had such a hard time of it, that Jim didn't, and that his friend was just floating along easy as pie. This simple line puts that idea to rest, showing Huck that Jim had his fair share of problems on the raft and that he probably couldn't have, as Huck wanted, spent the entire banging a pot. He had a pretty rough time of it.
"We would sell the raft and get on a steamboat..."See in text(Chapter XV)
Twain uses the idea of Cairo and the steamboat to solve a problem: his characters can't possibly want to sail to the Mississippi and follow it, because the South would be even worse for a runaway slave than his owner's home. Here, their plan is to alter the course and go north to the free states; but, given Twain's personal experiences on the Mississippi River, we can assume that his characters are going to spend most of their time there.
"the old regular Muddy..."See in text(Chapter XVI)
The big Muddy, the nickname for the Mississippi River, the river Twain sailed as a steamboat pilot. Their plan was to catch a steamboat well before reaching the Mississippi and ride it up to the free states; but now that they've passed Cairo their only choice is to go South on the big Muddy (unless, of course, they abandon the raft there and travel by foot in a slave state, which wouldn't work out well for Jim).
"there's something up there that 'll help them think so..."See in text(Chapter XVIII)
It's unclear exactly what this would be. Huck didn't fake his death the way he did at Pap's place, and there aren't any unidentifiable bodies on the shore that could be mistaken for Huck's. It could be that Twain is relying on the fact that Huck has already faked his murder once to make the reader assume that he has done it again here; but there is no concrete evidence that Huck has faked his death, so we're left to conjecture.
"I 'uz off too fur to hear what dey say to you..."See in text(Chapter XVIII)
Recall that Colonel Grangerford's exact words in Chapter XVII were: "If there's anybody with you, let him keep back—if he shows himself he'll be shot." It's lucky, then, that Jim was wounded and afraid of the dogs, because if he had even attempted to reach Huck, he would've been killed. This is a fine example of how the misunderstandings in this novel can lead its characters into dangerous (even deadly) situations.
"and, by jings, it was my old Jim!..."See in text(Chapter XVIII)
Jim appears just as a secret is about to be revealed about the feud and Miss Sophia, thus heightening the suspense and distracting the reader (and Huck) long enough for Miss Sophie to make her meeting at half past two. Twain distracts Huck with "water moccasins" rather than, say, bunnies, because when one is primed to meet something as dangerous as a snake one isn't expecting that snake to be sweet, nice, gullible Jim, whom Huck seems to have forgotten about in the midst of this feud.
"Don't anybody know?..."See in text(Chapter XVIII)
Twain uses this senseless feud to both tragic and comedic effect: it's absolutely absurd that these families would blithely go around killing each other for no reason, and it's tragic because now the younger is paying for something that the older generation hasn't even bothered to remember. Huck's confusion about this feud further aligns him with the reader, who is also skeptical of the feud's efficacy.
Notice the use of the conditional "would" here. Twain transitions from a passage of lyrical beauty about a single point in time (watching the sunrise) to one where he uses "would" to establish a kind of routine: Huck and Jim would set the lines, they would go to sleep. In this way, Twain indicates that time is passing without having detail every minute of these three lazy days.
"show this handbill and say we captured him up the river..."See in text(Chapter XX)
This plan might seem ingenious in that it hides Jim in plain sight, but, in reality, it's likely to cause more problems for Jim by making random people think that they can make money off him. Without weapons on the raft and a commitment to defend Jim, it's possible that he will get captured by those attempting to collect the reward for themselves.
"and he was home now to take out some fresh men..."See in text(Chapter XX)
It's lucky, all things considered, that the audience seems to forget this part of his impromptu speech, and that no one offers to join his crew and become a pirate. Had this happened, the King would've had to elaborate on his lie, which, as the reader knows, only makes it less believable over time. Knowing this, the King makes a point of saying that his will be a long and arduous journey, in the hopes that this will deter anyone from joining him.
"runaway niggers on them, all over the walls..."See in text(Chapter XX)
This doesn't bode well for Jim. Everywhere they go in the South, he's going to be a fugitive, so his only options are to go back north to the free states or live his life on that raft forever, barring an unexpected bit of good luck. Huck may have fooled the King and the Duke into thinking that Jim is his slave, but it's possible that they'll see through his lies just as he saw through theirs. Jim must be very, very careful in this racist society.
"saying they believed he was a runaway nigger..."See in text(Chapter XX)
Huck's story is designed to protect Jim in the event that someone does find out that he's a runaway slave. Now that the King and Duke have heard this story, they can vouch for Jim, shielding him from the men who would take him away from Huck (while handily preventing the King and the Duke from selling him themselves).
"The streets was full, and everybody was excited...."See in text(Chapter XXI)
Keep in mind that the King and the Duke still fully intend to put on the play, and that this dramatic murder will be a hard act to follow. These townsfolk have revealed themselves to be a loud, riotous bunch with a penchant for getting into trouble and becoming violent at the drop of a hat. It's perhaps not the best decision to fleece these people, but the King and the Duke intend to anyway.
"down the state of Arkansaw..."See in text(Chapter XXI)
Geographically speaking, Huck and Jim have reached a point where they need to start thinking about what will happen when they reach the mouth of the Mississippi River. They're already in the Deep South, and pretty soon they'll hit Louisiana, where the handbill says Jim was a slave. This is the time for them to turn around, but instead they proceed with this absurd play.
"and everybody just a-howling with pleasure and astonishment..."See in text(Chapter XXII)
Twain juxtaposes this episode with the "drunk" circus performer and the scene with Boggs to show us how things should've gone: Boggs would've been drunk and harmless to anyone but himself, the crowd would've gotten a good laugh, and nobody would've died. Instead, the Sheriff had to take a hard line with Boggs, and it ended in tragedy.
"then dived in under the tent..."See in text(Chapter XXII)
Twain juxtaposes Sherburn's long speech about courage and moral fortitude with a short scene of Huck bending the rules in order not to pay to attend the circus. His moral relativity in this instance tempers the somewhat judgmental tone Huck has adopted in these past two chapters and reminds the reader that Huck doesn't have the moral high ground. He's a scamp, too, just of a different kind.
"Buck Harkness, there..."See in text(Chapter XXII)
Note that Buck Harkness was not actually the one who instigated this lynch mob. In the previous chapter, Twain simply said that someone suggested Sherburn be lynched without specifying who had the idea first. Thus, Sherburn's speech, though it might seem forceful and discerning, is based on faulty logic, and if he didn't happen to also be right about these men being cowards, they would've lynched him for calling them out.
"mention it to their friends..."See in text(Chapter XXIII)
This is both a dangerous and a clever suggestion, because it has the potential to start a mob like the one we saw in the previous chapter while at the same time reminding the audience that other people in town haven't seen the performance and will laugh when they hear that their neighbors were swindled by these buffoons. It remains to be seen if this gamble will work out in the Duke and King's favor.
"and pretty soon she got off..."See in text(Chapter XXIV)
Keep in mind that the steamboat's departure also marks the exit of the only townsperson who knows the King's fake identity, Reverend Elexander Blodgett, and that, with this young man gone to Brazil, the King is now free to impersonate Peter's brother without anyone else knowing about this interrogation or his intent to steal Peter's money. Huck is now the only one who can stop this from happening, and it remains to be seen if he will.
"THE NEWS WAS ALL over town in two minutes..."See in text(Chapter XXV)
Twain implies that this town is small by saying that news spread over it in a very short period of time. This establishes that not only is this a small town, but that the people in it all know each other well enough and gossip frequently enough that nothing can happen here without everyone knowing about it. This is Twain's subtle way of establishing the setting.
"I'm letting him rob her of her money..."See in text(Chapter XXVI)
Twain’s use of repetition here helps us better understand Huck’s mental state. Now that Huck sees that Mary Jane has a kind heart, he is almost at a point of disbelief at the duke and king’s con. Huck has slowly been feeling more and more of the injustice of the duke and king’s tricks, and Twain’s repetition subtly reveals that Huck might be working himself up to do something about it.
"“Well, I see the niggers go in there several times.”..."See in text(Chapter XXVII)
This is very sneaky of Huck and again illustrates his cleverness. The slaves were sold to Memphis and New Orleans and are already gone by the time the king questions Huck. Thus, the slaves Huck wrongfully accused will not be punished, but Huck will not be discovered either, as we can anticipate that the king is likely to believe Huck’s lie due to his prejudice beliefs about African Americans.
"that nobody hadn't hired me to take care of..."See in text(Chapter XXVII)
Huck’s actions might be noble, but he faces a serious threat if he is caught. As his stealing the money from the duke and king would surely make them angry, they would be much less obliged to use their talents for deception to help Huck if he were caught. Twain points out that no good deed goes unpunished—and no one would take the word of a young, poor valet over the word of “Wilks’ brothers.”