In reading the passage about the jump more carefully, it seems to me that Louisa jumps twice from the same height: In all their walks he had had to jump her from the stiles; the sensation was delightful to her. The hardness of the pavement for her feet made him less willing upon the present occasion; he did it, however. She was safely down, and instantly to shew her enjoyment, ran up the steps to be jumped down again.
I must have been influenced by P2 because I thought the second jump was from higher up on the steps. It doesn't say this, though, so now I'm thinking she jumped the first time and landed safely & then ran up to the same height to be jumped down again. Seems to make the Captain a little less culpable, hmmm?