From the post:
As well as providing tools to visualise the metadata, in bringing together detail on sender, recipient, place and date for over 150,000 letters for over twenty collections, Visual Correspondence provides a new way to explore the letters themselves. Where possible, links back to the original texts are provided. Also using data from Wikipedia, biographical information and more has been added to put the letters themselves in more context. Hopefully in exploring this site, the user will begin to see letter writing for the valuable part of our history that it is.
See the resource here: Visual Correspondence: Analysing Letters through Data Visualisation – Data Visualisations by Niall O’Leary