7* SELECT EXERCISES.

An Orrery, Jh.civing the Motions of the Sun %Mercury, Venus, Earth, Moon, and Nodes,of the Moon’s Orbit ; the different Lengthsof Days and Nights , the Vicissitudes ofSeasons, Age and Phases of the Moon, andall the Solar and Lunar Eclipses.

The use of this Orrery, and thematiner of using it, being already de-scribed in my Astronomy, I shall notrepeat those matters here; but shallOnly describe the wheel-work of it,which is not done in that book. It ishot copied from any other Orrerywhatever, and I can with truth fay,that it shews the revolutions of theMoon and Planets nearer the truththan any other Orrery does, that hasfallen under my examination. I there*fore freely give the following accountof it to the Public, in the best mannerthat I can; and do wish the descrip-tion may be generally understood. To