11. In the Hipparchian system the epicycle rotated and revolved along the deferent with uniform motion. 12. Deferents and epicycles in the ancient models did not represent orbits in the modern sense. 13. That seems to contradict Deferent and epicycle . 14. A Spirograph pattern is just one epicycle . 15. Copernicus eliminated Ptolemy's somewhat-maligned equant but at a cost of additional epicycles . 16. Various 16th-century books based on Ptolemy and Copernicus use about equal numbers of epicycles . 17. Ptolemy described lunar motion by using a well-defined geometric model of epicycles and evection. 18. epicycles using the Tusi-couple, thus eliminating the Ptolemaic eccentrics and equant . ]]19. :: : That article states that retrograde motion was used to develop the epicycles system. 20. Astronomers responded by introducing the deferent and epicycle , which caused a planet to vary its distance.
