Primary source. Very much primary source. Which makes that it was published in 1860 noticeably important.
Conveys a great deal of what society was like, with all the usual caveats about descriptive vs. prescriptive. Like her dwelling on this
Never, in speaking to a married lady, enquire for her husband, or, if a gentleman, ask for his wife. The elegant way is to call the absent party by their name; ask Mr. Smith how Mrs. Smith is, or enquire of Mrs. Jones for Mr. Jones, but never for "your husband" or "your wife." On the other hand, if you are married, never speak of your husband as your "lord," "husband," or "good man," avoid, also, unless amongst relatives, calling him by his Christian name. If you wish others to respect him, show by speaking of him in respectful terms that you do so yourself. If either your own husband or your friend's is in the army or navy, or can claim the Dr., Prof., or any other prefix to his name, there is no impropriety in speaking of him as the colonel, doctor, or whatever his title may be.
may indicate that the opposite usage was common.
And it's interesting to note that she expects the bridesmaids as well as the bride to wear white, albeit perhaps with colored ribbons. And when she writes about letters, we can see technological change in progress:
If you use an envelope, and this custom is now universal, fold your letter neatly to fit into it; then direct on the envelope.
The chapter on accomplishment lists in detail directions for knitting certain things and the like. And this anecdote recounts the importance of getting out of the carriage.
How to get in is difficult, but of less importance than getting out; because if you stumble in, no one sees you, but some one who may happen to be in the carriage; but how to get out is so important, that I will illustrate it by a short diplomatic anecdote:—
"The Princess of Hesse-Darmstadt," says M. Mercy d'Argenteau, an ambassador of the last century, "having been desired by the Empress of Austria to bring her three daughters to court, in order that her Imperial Majesty might choose one of them for a wife to one of her sons, drove up in her coach to the palace gate. Scarcely had they entered the presence, when, before even speaking to them, the empress went up to the second daughter, and, taking her by the hand, said, 'I choose this young lady.' The mother, astonished at the suddenness of her choice, inquired what had actuated it. 'I watched the young ladies get out of their carriage,' said the empress. 'Your eldest daughter stepped on her dress, and only saved herself from falling by an awkward scramble; the youngest jumped from the coach to the ground, without touching the steps; the second, just lifting her dress in front, so as she descended to show the point of her shoe, calmly stepped from the carriage to the ground, neither hurriedly nor stiffly, but with grace and dignity: she is fit to be an empress; her eldest sister is too awkward, her youngest too wild.'"