Note 298 — 357ON THE COMMONWEALTH.

Cicero here gives a very exact and correct account of the planetarium of Archimedes, which is so often noticed by the ancient astronomers. It no doubt corresponded in a great measure to our modern planetarium, or orrery, invented by the earl of that name. This elaborate machine, whose manufacture requires the most exact and critical science, is of the greatest service to those who study the revolutions of the stars, for astronomic, astrologic, or meteorologic purposes.