A review of reconstruction research for the lost gearing of antikythera astronomical calculator

This paper presented a review for the reconstruction research of the Antikythera mechanism, the mechanical calculator was made around the end of second century BC in ancient Greece. Under the concluded design specifications and constraints, all possible conceptual designs of the lost mechanical structures subject to the standard of technology and science at that time were synthesized based on a systematic design procedure. This oldest astronomical calculator excavated in 1900-1901 can display the solar, lunar and planetary motions, indicate the date of Egyptian calendar, calculate the luni-solar calendars and periods, and predict the eclipses by its interior gear trains. The structures for the solar and the planetary motions are completely lost in the excavation. Without surviving evidence, restoring the lost structures by computer tomography or X-ray detection is unfeasible. Here, the author applied a design procedure with four steps, which is based on the reconstruction design methodology of lost ancient machinery. Historical archives for reconstructing Antikythera mechanism are built based on historical records, ancient astronomy, ancient astronomical instruments, as well as the kinematic and mechanism analyses of gear trains. After identifying input conditions, three and two design specifications respectively for the solar and the planetary motions are concluded and their feasible designs are synthesized by the design procedure. For each design, the equations of teeth counting are derived based on the analysis of gear ratios. Finally, the possible teeth of gears are generated and then a new reconstruction design of Antikythera mechanism with complete interior structure is built through the constraints of space and assembly. These synthesized designs form a database of reconstruction work, and one of them can be the original structure. Once new evidence is discovered, these reconstruction designs can help archaeologists decode this mechanism further.