Shall and will -- a distinction lost to the ages, but interesting

The rules below are from a "Concise Handbook of Composition," 33 pages at the end of Ways of Thinking and Writing by Phillips Exeter Academy professors Frank W. Cushwa and Robert N. Cunningham (Charles Scribner's Sons, 1936).
The distinction between "shall"and "will" is pretty much lost to the ages -- but it can be interesting to us as grammar historians.

III. Usage
22. Remember the rules for shall and will.
(a) To indicate merely that action will take place in future time, use
I shall . . . . . . we shall
thou wilt (you will) . . . . . . you will
he (she, it) will . . . . . . they will

(b) To indicate that the speaker is determined to do a thing or to have it done, is willing to do it, or is making a promise, use

I will . . . . . . we will
thou shalt (you shall) . . . . . . you shall
he (she, it) will . . . . . . they shall

(c) In questions, use shall in the first person in the first person except when the speaker is repeating verbatim a question which has just been asked him. In the second and third persons, use the auxiliary which, in accordance with rules (a) and (b), would naturally be used in the answer. The person of the question will often differ from that of the answer.

Examples:

• Where shall I leave your books? [Not Where will I?]
• Will I go? I certainly will. [The speaker echoes the original question.]
• Shall you be in Boston on Saturday? If all goes well, I shall. [The answer indicates simply that the speaker expects to be in Boston on Saturday.]

Will you meet us in town? Yes, I will. [That is, I promise to.]

(d) In an indirect statement, use the auxiliary which would be required if the statement were direct. The person of the original verb changes to suit the indirect discourse.

Examples:

• He says that he will attend to my case at once. [The speaker said, "I will (that is, I promise to) attend to your case at once."]
• He says that hirhday next month. [The direct statement was, "I shall have a birthday next month."]
  
  NOTE 1. Should and would follow the same rules as shall and will except when should expresses obligation [No man should forget his duty to his country], or when would indicates customary or habitual action [I would sit by the hour playing my flute].
  To express obligation, use should in all three persons. To espress customary action use would in all three persons.
  
  NOTE 2. I would like, a common error, is always wrong. In would and like the idea of volition is expressed twice. Say always, "I should like."
  
  Here in the 21st Century, we can all ask, "Who knew?"