ORRERY

A machine for representing to children the motions and relative magnitudes and distances of the bodies composing the solar system. As these machines are often procured by well-meaning but ignorant people at considerable expense, it may be useftil to quote an authority that will not be called in question. " As to getting correct notions on this subject " (the magnitudes and distances of the planets), says Sir John Herschel, •' by drawing circles on paper, or, still worse, from those very childish toys called orreries, it is out of the question." {Astronomy, Cab. Cyc. p. 287. J"or the description of an orrery see Ferguson's Astronomy, by Brewster.; [s. 872]