LENS n.
er both curved, or one curved and the other plane, and commonly used, either singly or combined, in optical instruments, for changing the direction of rays of light, and thus magnifying objects, or otherwise modifying vision. In practice, the curved surfaces are usually spherical, though rarely cylindrical, or of some…
MONAD n.
An atom or radical whose valence is one, or which can combine with, be replaced by, or exchanged for, one atom of hydrogen. Monad deme (Biol.), in tectology, a unit of the first order of individuality.