Both entries for the Incarnation follow from the standard Alfonsine table for the radices for places other than Toledo for a geographical longitude of 32°.6 This is exactly the longitude of Ferrara given in Bianchini's text (Introduction and Chapter 1), but differs from that assigned to Ferrara (33;30°) in the table for geographical coordinates, which is only included in ed. 1526 (see Table 87, below). The difference in longitude between Toledo and Ferrara is 21°, and corresponds to adjustments of -0;3,27° and +0;0,11° in the values for the mean motion of the Sun and the lunar node, respectively.
The entries for the radices in 1400 and 1440 in Table 5 are obtained by adding those for the Incarnation (computed for a geographical longitude of 32°) to those corresponding to 1400 and 1440 years in the table of the mean motions. Thus, for 1400 we find for the Sun and the lunar node, respectively:
4,48;34,42° = 4,38;17,34° (Incarn.) + 7;20,48° (1000y) + 2;56,20° (400y), and
2,50;5,25° = 1,31;55,42° (Incarn.) + 4,21;32,39° (1000y) + 2,56;37,4° (400y),
6 Ratdolt, Tabule astronomice Alfontij, d1v-d2v; see also Poulle, Les tables alphon-sines, 127-29.
in agreement with the tabulated values. We note, however, that these values correspond to the positions of the Sun and the lunar node for 1400 complete years after the Incarnation, not at the beginning of year 1400. Thus the 'radices for 1400', as expressed by Bianchini, have to be understood as the values at the beginning of year 1401 for a place at geographical longitude 32°.
Table 6. Mean motion of the Sun and the lunar node in days
Na, f. 15v: Tabula solis et capitis draconis Nu, f. 30r: Tabula veri motus capitis draconis
Va, f. 186v: Tabula motus [symbol for the Sun] et [symbol for the ascending node] draconis Ed. 1495, f. a7r: Medii motus in diebus Ed. 1526, f. 7r: Medii motus in diebus
This table, with the same layout as that of Table 4, gives the mean motion of the Sun and the lunar node for a number of days (in decreasing order, from 300d to 100d at intervals of 100d, from 100d to 10d at intervals of 10d, and from 10d to 1d at intervals of 1d): see Table 6. In MS Nu only the mean motions of the lunar node from 1d to 31d, at intervals of 1d, are given.
Lunar node (°)
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