Mark Godburn of earlydustjackets.blogspot.com posted on December 13, 2011:
"1819, 1822 & 1829. Earliest publishers' jackets.
"J. C. Osterhausen and G. C. Wilder. Nürnberg: Bei Riegel und Wießner, 1819 & 1822. Two vols. complete. First edition. Paper covered boards. Illustrated. [The Bookmark]
"Each volume has its original plain jacket and slipcase with label. These are now the earliest recorded publishers' jackets. The record was previously held by a sealed wrapping jacket issued late in 1829 on an 1830 British annual. The image at left shows the books in the center, with the slipcases at the outer left and right. The 1822 volume to the center left is wrapped in its light blue jacket; the 1819 volume to the center right has its dark blue jacket open, with a small part of the flaps visible behind. The slipcases are each covered in the same light blue paper as the jacket for the 1822 volume, with the color faded on the outside. A second edition of the first volume was issued in 1829 in a jacket of the same cut with narrow beveled flaps, and a slipcase with the same label as the 1819 slipcase."
This discovery put the early introduction of publishers' jackets before the introduction of publisher's cloth as a permanent binding material in the 1820s.