Over the past couple of years I have been researching and writing a book about the fifteenth-century German printer, Erhard Ratdolt. He printed over 200 titles during his career, and part of my work is to study the content and typography of as many of those editions as possible. Recently, while writing a chapter titled, Printing the Heavens — about Ratdolt's books on astrology and astronomy — I noticed a capital letter Z that had been printed in reverse. I checked the other 120 pages of this book to discover it was the only capital Z in the entire volume.
Curiously, however, there also appears a woodcut initial Z, in the same book, that too is printed in reverse. There are numerous lowercase z's, but these are all printed in the correct orientation.
There are two possible explanations for this curious capital Z: first, that it was simply an accident on the part of the type maker (it was miscast); second, that it was a stylistic preference, that the capital Z was intentionally set in reverse. So I began to look for other examples of reversed Z's. But before that, it's worth mentioning a pirated version of Ratdolt's 1485 Hyginus put out by Thomas de Blavis in 1488 (who at least had the good sense to publish his edition after Ratdolt had left Venice to return to his hometown of Augsburg around 1486). In Blavis's knock-off, he copies Ratdolt's woodcut illustrations and text and, incredibly, even copied the reversed Z from the Ratdolt edition. Therefore, Ratdolt's Hyginus of 1485 and Blavis's pirated Hyginus of 1488 are the only two examples of incunabula books, that I know of, with a reversed capital Z.
There are almost 30,000 extant incunabula (fifteenth-century) editions. Checking every single one was impractical to say the least. But the task is made easier in that only about 20% of incunabula editions are printed in roman, and of those only a small proportion were likely to include a capital letter Z — owing to the rarity of the letter z in Latin, which is mostly used for proper nouns and nouns of Greek origin like Zodiac[us]. So I narrowed my search to books about astrology and astronomy, printed in roman type. Of those I took a random sample of 20 titles and scanned all pages for capital Z's. I found no other examples of reversed capital Z's, so we can safely assume that the reversed Z in Ratdolt's edition was set thus in error — probably by a type-cutter unaccustomed to cutting and casting capital Z's. It could not have been a simple error on the part of the compositor (the person who sets the type in the forme), as the shoulder of the type would result in the Z dropping below the baseline (and an upside-down Z is still a Z):
However, in the thoroughly boring task of searching 500-year old books for capital Z's, I did discover something else. Most fifteenth-century fonts did not include a letter Z, simply because, as already remarked, it was rarely required. But if, as a printer, you only possessed Z-less fonts, what were you to do when Giovanni requested 200 copies of a work on Astrology? Well, you could do as Anton Koberger did in this 1486 edition of Registrum in Cosmographiam Ptolemaei, and simply rotate a capital N.
And the letter N wasn't the only letter to be mangled in this manner. How about this innovative, yet less convincing appropriation of an italic A for V in Venetia (Venice):