Franz Xaver Kugler demonstrated in his book "Die Babylonische Mondrechnung" (""The Babylonian lunar computation"", Freiburg im Breisgau, 1900) the following: Ptolemy had stated in his "Almagest" IV.2 that Hipparchus improved the values for the Moon's periods known to him from "even more ancient astronomers" by comparing eclipse observations made earlier by "the Chaldeans", and by himself. However, Kugler found that the periods that Ptolemy attributes to Hipparchus had already been used in Babylonian ephemerides, specifically the collection of texts nowadays called "System B" (sometimes attributed to Kidinnu). Apparently, Hipparchus only confirmed the validity of the periods he learned from the Chaldeans by his newer observations.