Right on cue, I figured out the letter that comes after P.
Antonio Basoli (1774–1848) was an Italian painter, engraver, professor, and set designer. He also decorated theaters and palaces. Here's an example of one of his set designs:
It's not too big of a leap from there to his Alfabeto Pittorico (Pictorial Alphabet), 1839:
* You can see the whole alphabet here
* Amazon sellers have 2 copies
* Calligraphy and a calligram