In a mid-fourteenth century manuscript housed at the British Library,  Add MS 10027, an anonymous chronicler recounts the events of the northern Italian city of Pisa, 1191-1337. The text is written in a neat book hand, austere and without rubrication or decoration. Blocks of near-illegible  mercantesca occasionally grace the texts margins, and a sporadically uneven number of lines can be found on each folio. Compounding the impression of the text as haphazard and disorganized, some long-forgotten archivists have numbered it according to two conflicting foliations. Despite the relative humility of this copy of the chronicle, the historical text reflected in Add MS 10027 is not otherwise unknown; a printed version of the work was published in 1738 as  part of the Rerum Italicarum Scriptores (hereafter, RRIISS), a series dedicated to publishing historical sources from the Italian peninsula.
For the moment, only these two versions of the chronicle are known to us - the manuscript version, listed in the British Library catalogue as HISTORIA VERA de comite Ugolino, qui cum filiis misericorditer finiit in civitate Pisanorum ;-A chronicle of Pisa, from the year 1191 to the year 1337; in the Pisan dialect. Quarto. [10,027.], and the printed one, published as the Fragmenta Historiæ Pisanæ, Auctore Anonymo. Since we were interested in exploring the ways in which the chronicle's author reckoned with time, it was important for us to discern whether the two witnesses contained any textual differences. In the process of investigating this, we discovered important disparities between the two versions that relevant to our project and have the potential to be of importance for future research.

The RRIISS version must have relied on a different manuscript than the text in the British Library manuscript. While we do know that the manuscript version is older than the printed RRIISS version, we do not know the age of its source manuscript relative to the one housed at the British Library. Furthermore, we have as yet been unable to determine which manuscript the editor of the RRIISS used to create his edition.

Before doing this, the texts had to be prepared for digital comparison. Since we only had access to images of the manuscript version, we first transcribed the text using FromThePage to create a digital copy. The RRIISS version was available as a PDF from Archive.org, which we ran through ABBYY Fine Reader to perform optical character recognition (OCR). As with many OCR transcriptions, this one needed human revision. which we  conducted in FromThePage. This process of manual transcription and correction provided us with an opportunity to become familiar with the peculiarities of the manuscript, such that more than the narrative content, the patterns and formulae, regularities and irregularities of the composition, became apparent. This familiarity with the layout and focus of the two textual witnesses was invaluable when determining the differences between them.

The work of scanning the two witnesses for textual differences was done in Kaleidoscope, a tool which is described in more detail in the technological process section of this book.

Based on the results of this comparison, there is evidence to suggest that the RRIISS version came from a different manuscript copy from the British Library's manuscript. While we do know that the manuscript version is older than what is found in the RRIISS, we do not know the age of the manuscript that it is taken from relative to the British Library's manuscript. We have also as of yet been unable to locate the manuscript used to create the RRIISS edition.

The differences discovered are important because scholars analyzing the chronicle in their work cite the RRIISS version. By making a second  (and, we will argue, superior) witness to this text available to historians, we demonstrate that the RRIISS version should not be considered definitive in Pisan historiography.