One concerns a seaport in Spain:
There was an Old Person of Cadiz,In Spanish this place is spelt Cádiz and correspondingly pronounced ˈkaðiθ, or locally ˈkaðis. As shown by his rhyme, Lear must have called it ˈkeɪdɪz. In contemporary English, though, it is usually called kəˈdɪz, which is scarcely closer to the Spanish than Lear’s version. Why have we modernized the pronunciation by switching the stress to the wrong syllable?
Who was always polite to all ladies;
But in handing his daughter,
he fell into the water,
Which drowned that Old Person of Cadiz.
Places of this name in the USA may retain the earlier pronunciation.
The other relates to the city that is now the capital of the Czech Republic.
There was an Old Person of Prague,The Czech name is Praha, pronounced ˈpɾaɦa. Lear evidently said preɪɡ. This variant is mentioned by Daniel Jones in EPD as late as 1963: although giving only the pronunciation prɑːɡ, he adds the note “There existed until recently a pronunciation preiɡ which is now probably obsolete”.
Who was suddenly seized with the plague;
But they gave him some butter,
which caused him to mutter,
And cured that Old Person of Prague.
In the case of Copenhagen, interestingly enough, the innovating form with -ˈhɑːɡ-, despite being popularized by Danny Kaye, has not succeeded in displacing traditional -ˈheɪɡ-. And we still call Den Haag / ’s-Gravenhage by the name The Hague heɪɡ.
I expect that Lear, like other early Victorians, would also have rhymed Rome with loom and tomb, Milan with Dillon, and Calais with Alice. Again, the latter persists right up to the 1963 EPD, where it is characterized as no more than “old-fashioned”.