A central image of the novel is reinforced in the last three paragraphs of Chapter 13. What is the image? List two Twain reinforces this image?

It's the ferry boat limping along. What "two" do you mean? Do you mean ways?

I meant what 2 ways does he reinforce this

I like this sentence,

"Well, before long here comes the wreck, dim and dusky, sliding along down! A kind of cold shiver went through me, and then I struck out for her."

Note the alliteration (dim /dusky) has an ominous ring to it. Words like "cold" and "shiver" reinforce the ship as a damned vessel.