Printer Erhard Ratdolt's edition of Eusebius of Caesarea's (Eusebius Caesariensis) Chronicon issued from Venice on September 13, 1483 recorded an entry for the year 1440 added by the editor, Johannes Lucilius Santritter of Heilbronn, crediting Johann Gutenberg, with the invention of "an ingenious way of printing books." This was one of the earliest acknowledgments in print of Gutenberg's invention.
"This statement apparently influenced the account in the 1499 Cologne Chronicle, where it is stated that the printing process was 'developed' ('Wart undersoicht') in the year 1440 and after, whereas printing was 'begun' ('do began men tzo drucken') in the jubilee year 1450 and after.
"If this statement is correct, it must refer to the period when Gutenberg was living in Strasbourg and when, as now-lost Strasbourg documents show, he was involved in teaching certain investors several mechanical skills, including gem cutting and polishing. A deposition in a lawsuit brought against Gutenberg makes reference to 'four pieces lying in a press' and to Gutenberg's wish that they be taken out and separated so that their purpose would not be known. Many generations of investigators assumed that this statement referred to typographic experiments, and they have elucidated in detail what the four pieces 'must' have been. However, Kurt Köster has showed that Gutenberg's major Strasbourg undertaking of the late 1430s was the mass production of pilgrim mirrors in anticipation of the Aachen pilgrimage, and he has argued convincingly that all the vocabulary of the lawsuit in question could apply plausibly to this enterprise, not to typographic experiments. The argument does not entirely invalidate the possiblity that in 1440 Gutenberg was experimenting with typography. But there is no proof, and all the earliest physical survivals in typography have a Mainz, not a Strasbourg, context" (Paul Needham, "Prints in the Early Printing Shops," IN: Parshall (ed) The Woodcut in Fifteenth-Century Europe  44).
ISTC no. ie00117000. In February 2015 a digital facsimile of physician Hartmann Schedel's copy of Ratdolt's edition was available from the Bayerische Staatsbibliothek, München at this link. The utility of Eusebius's text to Schedel, author of the Nuremberg Chronicle, is evident.