Claudius Ptolemy refined the deferent / epicycle concept and introduced the equant as a mechanism for accounting for velocity variations in the motions of the planets.
42.
Al-Tusi found a way to restore most of the symmetry to Ptolemy's model by adding pairs of cleverly designed epicycles to each orbit.
43.
The angular rate at which the epicycle traveled was not constant unless he measured it from another point which he called the " equant ".
44.
In keeping with past practice, Copernicus used the deferent / epicycle model in his theory but his epicycles were small and were called " epicyclets ".
45.
In keeping with past practice, Copernicus used the deferent / epicycle model in his theory but his epicycles were small and were called " epicyclets ".
46.
For example, it was Ibn al-Shatir's concern for observational accuracy which led him to eliminate the epicycle in the Ptolemaic lunar model.
47.
However, if either is actually enacted, we will need a whole new set of epicycles within epicycles to incorporate them into the already unwieldy tax system.
48.
However, if either is actually enacted, we will need a whole new set of epicycles within epicycles to incorporate them into the already unwieldy tax system.
49.
The classical Greek concepts of deferent and epicycle in the Ptolemaic system of astronomy were related to Fourier series ( see Deferent and epicycle : Mathematical formalism ).
50.
The classical Greek concepts of deferent and epicycle in the Ptolemaic system of astronomy were related to Fourier series ( see Deferent and epicycle : Mathematical formalism ).
