Writing style before Elements of Style

Question

I am looking for the representative references on writing style in English that would pre-date Strunk and White's The Elements of Style (possibly in the period between 1750 - 2000). I would like to understand the evolution of what was taught to be good style in written English before the only book on the topic that I know of.

British English references would be preferable, but American English is also welcome in the absence of European equivalents.

The reason:
I am working on a short novel where I have a long-lived character (born 1750 - dead 2000), who is described through her epistolary correspondence. The MC is convinced that there is a treasure hidden amidst all these letters. I wanted to give a bit of flavour to it. I can safely alter word usage to give a feeling of older times. I was hoping to be able to adapt the writing style as well.

So far:
I just browsed lazily through period texts. However, rather than imitate specific authors, I was hoping I could put myself in the mindset of an "average" learning writer of that time. [Note: keeping in mind that learning writers might have been far from average in the past]

Answer 1

Here are some books that should help. Where it makes sense, I'm trying to include the date and place of publication, a description, and a quote for context. (Not all of the information in these books will be helpful, unless you don't know what consonants and vowels are.)

A Key to the Art of Letters, 1700, London:

• Earlier than your timeframe but still worth mentioning because I have it.

  Q: What words are usually surprest [i.e. elided]?
  A:[...] That whatever word comes to be repeated in a Sentence oftner than once, it is seldom exprest but once, to avoid a repetition of the same word which is usually very inelegant and unpleasing to the Ear; as for example, This is my Master's Book, or this Book is my Master’s, for this Book is my Master’s Book.

The Royal Universal British Grammar and Vocabulary, 1754, London:

• Vocabulary, and some hyper specific questions about grammar, with answers.

  Q: Do there always follow a Name immediately after the Affirmation?
  A. Not always; for when the action or Affection of the Subject does not extend, or relate to some other Person or Thing, but terminates in the Subject itſelf, there is no Name required after the Affirmation.

  Examples

  I grieve.
  They stand. [...]

Johnson's A Dictionary of the English Language, 1755, London:

• It's a dictionary, not a style guide, but still offers advice on word choice. You wouldn't want to use a "low word", would you?

A Key to Letters, 1769?, Norwich

• I am not sure of the date on this one, but it's definitely 1769 or later (but not too much later.) This is also the book to look at if you need something that has both lessons on English and prayers for children.

  Note [...] That the long ʃ must never be inserted immediately after the short s nor at the end of a word.

The Complete Letter-writer, 1770, London:

• Covers the proper "stile" for letter writing, basic grammar, and also has a whole bunch of example letters for almost any purpose.

  When writing to your Superior... be particularly careful in not omitting any Letter belonging to the Words you write as I've, can't, don't, shou'd, wou'd, &c instead of I have, cannot, do not should, would, &c for such Contractions not only appear disrespectful and too familiar but discover those almost inseparable Companions Ignorance and Impudence.

An English grammar; methodical, analytical, and historical, 1874, London:

• It starts at the basics (if you don't know the alphabet why would you be able to read about it?) and covers a lot, including Old and Middle English.

  North-English dialects still have the preterite strave, formerly in use in Modern-English: Not us'd to frozen clips he strave to find some part (SYDNEY). Shakespeare inflected strive; strove; strove.

The Complete Art of Writing Letters, 1789, 1824, London:

• Also has "An agreeable Variety of Original Letters"!

The Comic English Grammar, 1845, New York:

• Despite being published in America, it says "American English is Comic English in a 'pretty particular considerable tarnation' degree", so... It has pictures and illustrations, which is the only thing you need to know.

  Very dreadful expressions are also used by draymen and others in addressing their horses. What can possibly induce a human being to say "Gee woot!" "Mather way!" or "Woa?" not to mention the atrocious "Kim aup" of the ignorant and degraded costermonger. We once actually heard a fellow threaten to "pitch into" his dog! meaning, we believe, to beat the animal.

The Art of Correspondence, 1884, Boston:

• Published in America, and mentions stuff about England. Also has sample letters, including love letters, because why not?

  Mr. is applied to men in all ranks, high or low, rich or poor, while Esq. is applied to persons of marked prominence in society. In England it applies to owners of landed estates, barristers-at-law, mayors, and commissioned officers in the Army and Navy, and professional men.

The Telegraph Instructor, 1901, Indiana:

• Like texting, but older.

  Example Sentences
  Hw sun wi 1st 74 b rdy — How soon will 1st No 74 be ready?

Modern English, book 2, 1905, London

• The book is focused on writing and grammar with plenty of exercises. The grammar terminology is mostly still used today, but even if you're not familiar with it, it's still easy to read. Later on, it has a couple examples of letters and telegrams

  Compound nouns, and expressions serving to name a single person or thing, add the possessive sign to the last word; as, my sister-in-law's letter; your brother George's mistake; the Duke of Wellington's. estate.

Correct English, 1906:

• Although it looks American, it says that it will be translated in German and distributed throughout the German Empire.

  DON'T SAY
  It is no use to do that.
  SAY
  It is of no use to do that.

Handbook of Present Day English Part 2, Part 3, 1931-1932:

• More

  The progressive when implying duration always refers to a limited time, but it may be used with such adverb adjuncts as always, constantly, perpetually, etc. expressing repetition.

Answer 2

Westlake, J. Willis (James Willis), 1830-1912, wrote at least three "how-to-write" books, including How to write letters: a manual of correspondence.

Answer 3

The Wikipedia history of campaigns against singular they gives quite a few examples of stylists from the eighteenth and nineteenth centuries. Note that prescriptions of language such as these rarely matched what common people actually said and wrote, and arguably had sexist motivations (for the particular case of third person pronouns). If you want to match common style your best strategy would be to immerse yourself in works from that era.