Mural circle, [61].
Nadir, the point in the celestial sphere directly beneath our feet, opposite to zenith.
Nebulæ, [217].
Nebular hypothesis, not atheistic, [182]; stated, [182]; confirmatory facts, [183]; objections to, [185].
Neptune, elements of, [175].
Node, the point in which an orbit intersects the ecliptic, or other plane of reference; ascending, descending, line of, [107].
Occultation, the hiding of a star, planet, or satellite by the interposition of a nearer body of greater angular magnitude.
Opposition. A superior planet is in opposition when the sun, earth, and the planet are in a line, the earth being in the middle.
Orbit, the path of a planet, comet, or meteor around the sun, or of a satellite around a primary; inclination of, [106]; earth's, seen from the stars, [70].
Outline for students, [276].