The immediate difficulty in dealing with Boulliau focuses on making sense of his manuscript remains--in identifying and locating his letters, in tracing and analyzing the various strands of his epistolary web.  But how are his letters to be brought into meaningful order?  His correspondence network rivals the combined efforts of Mersenne and Oldenburg with some 5,000 letters for the years 1632-1693.  Given the complexity and importance of Boulliau's network, it is useful to visualize its size and scope in simplest form - over space and time.

Several decades ago Robert Mandrou, the Annales historian, suggested a simple strategy for studying and evaluating correspondence networks.  The ingredients are simple enough. Mandrou traced the contours of the Peiresc network from existing lists of Peiresc's correspondents found at Carpentras.  In an effort to suggest the size and scope of Boulliau's network (if not its importance) I have provided a similar geographical map and temporal graph of letters to and from Boulliau known to have been exchanged over a period of sixty years.   It should also be noted that I have proceeded differently from Mandrou by plotting letters not simply their senders and recipients.  The difference is significant but even this strategy is not without serious deficiencies.  The following illustration is suggestive not exhaustive.  It represents letters from only the Collection Boulliau (some 4200) not other collections or locations.  However crude, it provides an outline in terra firma.