"shall" and "will" for 18th century BrEn readers: interchangeable?

[nekocat]

In Wuthering Heights rewritten for children I met with the following sentences, in which "shall" and "will" are used in a manner I can't understand if they are interchangeable. Are they interchangeable?

(1) If you won't lend me a guide, I will have to stay here.
(2) I feel I shall not rest if I go to bed.

 

[JimmySeal]

Both simply express the future tense. Shall is a hoity-toity old-fashioned way of forming the future tense, and there is little difference between "will" and "shall" here.

 

[nekocat]

Thanks and おおきに！
Are you sure (sorry, I really want to know) that for the author (in the 18th century) it wouldn't have made difference whether she would write "I will have to" or "I shall have to"?

 

[Sarapva]

"Shall" seems to be used more by the British than Americans. "Shall" and "will" could be interchanged today in those two sentences, but I don't know if they could be when the author wrote it. One example where "shall" can't be interchanged with "will" is in this sentence: "Shall we have tea or coffee?"

 

[nekocat]

ありがとう、Jimmy さんに Sarapva さん！
もう少し待ってみます。