digital preservation and computing history By Vaughan_Powell Jun 23, 1786 J.H. Muller Difference Machine concept Jun 14, 1822 Charles Babbage Difference Engine Concept Jun 2, 1849 Charles Babbage difference engine No.2 concept Jun 23, 1855 Per Georg Schutz - working difference engines Jun 23, 1901 Antikythera Mechanism discovered dated at early 1st Century BC Jun 23, 1991 Doron Swade - Reconstruction of working difference engine No.2
