We present digitization of a fragment of Diderot’s Encyclopedia which is related to mathematics. The digitization was performed during 2008/2009. at Mathematical Institute of the Serbian Academy of Sciences and Arts. The digitized material was included in the Virtual library of NCD [4]. More than a summary of all contemporary knowledge, the Encyclopedia served as a manifesto for a new way of looking at the world and played an important role in the intellectual ferment leading to the French Revolution. Some technical questions about compression of digitized files are discussed.