ASSEMBLING THE FRAGMENT D ON THE ANTIKYTHERA MECHANISM: ITS ROLE AND OPERATION IN THE DRACONIC GEARING

Abstract

The unplaced Fragment D of the Antikythera Mechanism with an unknown operation was a mystery ever since it was discovered. The gear r1, which was detected in Fragment-D radiographies by C. Karakalos is preserved in excellent condition, but this was not enough to directly relate it to the existing gear trains of the Mechanism. The suggestion that Fragment D could be a part of the hypothetical planet indication gearing is a hypothesis, in contradiction with the AMRP tomographies, and leads to mechanical malfunctions. The analysis of AMRP tomographies of Fragment D and its mechanical characteristics, revealed that it could be part of the Draconic gearing. Currently, the three lunar cycles Synodic, Sidereal and Anomalistic are represented on the Antikythera Mechanism. Although the Draconic cycle was well known during the Mechanism’s era as representing the critical fourth Lunar cycle, it seems that it is missing from the Antikythera Mechanism. The study of Fragment D was supported by our bronze reconstructions of the Fragment D, leading to the reconstruction of the Draconic gearing. These results are very important, because with the use of only one hypothetical/missing gear, the Draconic gearing is revealed on the Antikythera Mechanism. Fragment D(raconic) can be perfectly correlated with the Draconic cycle of the Antikythera Mechanism without mechanical problems and the four lunar cycles appear on the Mechanism. Based on the Draconic pointer, the eclipse events can be calculated and engraved on the Saros spiral cells.