Principia typographica : the block-books, or xylographic delineations of scripture history, issued in Holland, Flanders and Germany, during the fifteenth century, exemplified and considered in connexion with the origin of printing : to which is added an attempt to elucidate the character of the paper-marks of the period / a work contemplated by the late Samuel Sotheby, and carried out by his son, Samuel Leigh Sotheby.

Morgan copy includes additional proofs of title pages and plates, original tracings from which plates were produced, and manuscript letters to Sotheby describing copies and providing information for work. Manuscript notes throughout by S. and S.L. Sotheby. Volume I is entirely made up of manuscript correspondence, primarily post-publication orders and letters of congratulation. Vol. 4 (PML 3779) includes 5 leaves of 15th-century manuscripts of Donatus, Ars minor, primarily removed from bindings.
Netherlandish prototypography incunabula leaves removed from this work and catalogued separately: PML 2988-92/ChL 1615 and 1618-21.
Vol. 10 (PML 3785) is two wooden boards (15/16th-century?) with 3 leaves (leaves 39, 44, and 53 (i.e. leaves [4]/5, [4]/10, and [5]/5)) from the second Latin edition of the Speculum humanae salvationis (Netherlands, about 1474-1475) pasted on, heavily damaged and darkened. Recatalogued separately in the incunable collection as ChL 1614 (Copy 2).