Abstract

The following article has two parts. The first part recounts the history of a series of discoveries by Otto Neugebauer, Bartel van der Waerden, and Asger Aaboe which step by step uncovered the meaning of Column $$\varPhi $$ Φ, the mysterious leading column in Babylonian System A lunar tables. Their research revealed that Column $$\varPhi $$ Φ gives the length in days of the 223-month Saros eclipse cycle and explained the remarkable algebraic relations connecting Column $$\varPhi $$ Φ to other columns of the lunar tables describing the duration of 1, 6, or 12 synodic months. Part two presents John Britton’s theory of the genesis of Column $$\varPhi $$ Φ and the System A lunar theory starting from a fundamental equation relating the columns discovered by Asger Aaboe. This article is intended to explain and, hopefully, to clarify Britton’s original articles which many readers found difficult to follow.