N
(in the Ptolemaic system) a small circle, around which a planet was thought to revolve, whose centre describes a larger circle (the deferent) centred on the earth (托勒密体系)本轮
[astronomy]
As the terrains fly by beneath us, however, we begin to sense that Kaplan has laid out a vast, Ptolemaic astrolabe, with cycles and epicycles and turning inner orbits and mechanics of the sky, elaborating everything and explaining little.