The episodes with Tom Sawyer's scheme to enable Jim to escape is yet other examples of Mark Twain's satire upon the adventurous ideals of Romanticism, and are, therefore, meant to be ridiculous, just as is the Romantic "chivalry" of the feud between the Grangerfords and the Shepherdsons.
That Twain satirizes Romantic adventures is evinced by Tom Sawyer's literary-based strategies such as those that he suggests in Chapter 35: digging under Jim's bed with case-knives. When Huck suggests that it is foolish not to use picks and shovels, Tom retorts,
"It don't make no difference how foolsih it is, it's the right way and it's the regular way. And there ain't no other way, that ever I heard of, and I've read all the books that gives any information about these things."
When Tom finally realizes that they cannot reach Jim using only knives, they, then, resort to the logical method. After they crawl in under Jim's bed, they wake him and, instead of chiseling off the chain, Tom relates his plans to Jim.
1. Tom tells Jim to keep a jounal on a shirt that the slave Nat would smuggle in; on this shirt Jim must write in blood. Tom instructs Jim that he and Huck will make pies and such and smuggle in various things such as nails with which he can poke himself so he can write with his blood. (Of course, Jim would not know how to write, anyway.) The boys also have to fashion pens with which Jim can write on the walls just as Lady Jane Grey, Gilford Dudley and others have done in literature.
After great efforts, Tom and Huck use three washpans full of flour, getting burnt in the process as they cook pieces of a ladder in with the fashioned rope they have made. "We let on it took nine months to make it," Huck relates since Tom has instructed him that prisoners take years to escape in the novels.
2. In Chapter 38, Tom makes Jim carve on the walls and then he decides that Jim should create a coat of arms, underneath which Jim should write "a mournful inscription" such as this one, which Tom obviously has read in a novel:
Here, homeless and friendless, after thirty-seven years of bitter captivity, perished a noble stranger, natural son of Louis XIV.
Jim tells Tom that it would take him almost a year to
...scrabble such a lot of truck onto the logs with a nail, and he didn't know how to make letters, besides.
Tom then decides that they need a grindstone, but they are not strong enough to move it to Jim's shed, so they "fetch" Jim by raising the bed and sliding the chain off the bed leg and have him help them. Afterwards, they fix Jim's chain back on the bed as it has previously been.
These episodes satire the Romantic notions of people who lose all sight of what is practical and expedient.