A Revision for the Draconic Gearing of the Antikythera Mechanism, the eclipse events of Saros spiral and their classification

TL;DR

This paper proposes a revised mechanical gearing scheme for the Antikythera Mechanism's Draconic scale, enabling the calculation of eclipse events through phase correlation of lunar cycles, considering historical deformation effects.

Contribution

It introduces a new gearing scheme for the Draconic cycle in the Antikythera Mechanism, linking eclipse event calculations to phase correlation of lunar cycles and historical deformation.

Findings

Revised Draconic gearing scheme proposed

Eclipse events can be mechanically calculated via phase correlation

Historical deformation affects the Mechanism's accuracy

Abstract

Our research is focused on the missing, but important and necessary Draconic gearing of the Antikythera Mechanism. The three Lunar cycles Sidereal, Synodic and Anomalistic are represented on the Mechanism by correlating the Fragments A and C (part of the Front plate), whereas the fourth Lunar cycle Draconic results after correlating the unplaced Fragment D with Fragment A. Considering the deformation of the Mechanism s parts during 2000 years underwater and their shrinkage after their retraction from the sea bottom, we present a revised gearing scheme of the Draconic scale. The existence of the Draconic gearing is crucial, because both the preserved and the missing eclipse events can be precalculated by the phase correlation of three pointers: of the Lunar Disc, of the Golden sphere/Sun-ray and the Draconic. This means that the eclipse events are calculated by pure mechanical processing and that they are not documented observed events. The phase coordination of the three lunar cycles can be used as a quality criterion for a functional model of the Mechanism. Eudoxus papyrus was the key for the lost words completion of the Back Plate inscriptions eclipse events classification of the Antikythera Mechanism.