A Closer Look at Gear Calculations, Time Corrections, Escapements and Orbital Resonance

Abstract

A glance at the more comprehensive orreries that include all planets of the Solar System known at the time and many satellites, whether old or modern, tells us that they are built from a huge number of gears (cogs), pinions (cogged spindles), arbors and platforms each with its calculated angles, tilts and teeth. The complexity and precision engineering is clearly aimed at representing not just the relative positions of the bodies, but the times associated with them; about 365 days for the Earth to complete one circuit around the Sun, around 28 days for the Moon to rotate about the Earth and so on. While ancient civilizations were content to work with such approximations when they were discovered, accurate astronomical predictions demand more, much more.