Nominalists, a. [238].

Non-electrics, b. [194].

Numbers of the Pythagoreans, a. [82], [216].

Nutation, a. [465].

Nycthemer, a. [159].

Octaëteris, a. [121].

Octants, a. [180].

Oolite, b. [529].

Optics, b. [51], &c.

Organical sciences, b. [435].