AP9

Showing planetary motions in numbers

This double argument table is dedicated to the computation of Saturn true longitude. It has an interesting layout with red horizontal lines separating the different zodiacal signs and a vertical line marking a point where the longitude reaches a minimum and then begins to increase again, that is a stationary point of the planet. In other word this table offers some sort of numerical visualization of the main astronomical events the planet path in the sky undergoes.

The same type of tables are also copied for the four other planets and for their longitude. This original set of tables was designed by William Batecombe in Oxford around 1348. He was very likely inspired by John of Lignères Tabule Magne which were shortly before transmitted to England. With at least 36 witnesses coming from all parts of Europe the Oxford tables were one of the most diffused sets of Alfonsine astronomy, especially for their latitudes.