I first got the idea to collection hilarious 19th century book dedications from reading this Mental Floss article here. The first one is from their site, but the others have been cobbled together from various sources.
1.) Logan: a Family History, by John Neal (1822).
"I do not dedicate my book to any body; for I know nobody worth dedicating it to. I have no friends, no children, no wife, no home; — no relations, no well-wishers; — nobody to love, and nobody to care for. To whom shall I; to whom can I dedicate it? To my Maker! It is unworthy of him. To my countrymen? They are unworthy of me. For the men of past ages I have very little veneration; for those of the present, not at all. To whom shall I entrust it? Who will care for me, by to-morrow? Who will do battle for my book, when I am gone? Will posterity? Yea, posterity will do me justice. To posterity then – to the winds! I bequeath it! I devote it — as a Roman would his enemy, to the fierce and unsparing charities of another world – to a generation of spirits – to the shadowy and crowned potentates of hereafter. I—I—I have done – the blood of the red man is growing cold – farewell – farewell forever!"
2.) Cheveley, or The Man of Honour, by Rosina Bulwer Lytton (dedicated to her dirt-bag husband, Sir Edward Bulwer Lytton) (1839)
"To No One Nobody, Esq., of No Hall, Nowhere."
Bulwer Lytton was famously sensitive to his family's high status and sense of honor, so his wife is saying, "You're NOBODY. You ain't all that."
3.) Lady Windermere's Fan by Oscar Wilde (1892).
"Ladies and Gentlemen. I have enjoyed this evening immensely. The actors have given us a charming rendition of a delightful play, and your appreciation has been most intelligent. I congratulate you on the great success of your performance, which persuades me that you think almost as highly of the play as I do myself."
While not strictly a dedication, this was Wilde's formal address to the audience on the play's opening night.
4.) Any Wilkie Collins novel.
He writes long prefaces that basically amount to: "Critics: STFU–I checked with doctors/scientists/experts, and the improbable thing that happens in my book could ABSOLUTELY happen in real life, so don't even go there, you ignorant fuckers. Also, I wrote this book to solve ALL THE SOCIAL WRONGS, and if you cause these social wrongs, you're an asshole."
Because he's great like that.
I might be paraphrasing.
If anyone knows of any more, I will happily update this and give you credit! These are surprisingly hard to find.