Evershed, M. A. (Orr) · London : Gall & Inglis · leaf 185
r reversedher direction, but simply increased and retarded hermotion alternately during her monthly revolution.Thus, when the moon was at M, in what Ptolemy called 148 PTOLEMY. the upper apsis (or arc) of her epicycle, or as we shouldsay in her apogee, the motion on the epicycle was con-trary to… … Fig. 34. The moons epicycle and deferent. near the lower apsis, or perigee, and the motion on theeccentric seemed to be accelerated. The slight difference in speed between the two motionsaccounted for the continuous displacement of the apogeein the zodiac, as may be seen from the diagram.…
Dante Alighieri, 1265-1321 · Astronomy
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