Unaided
131Double refraction — Refraction Re*frac tion (r?*fr?k sh?n), n. [F. r[ e]fraction.] 1. The act of refracting, or the state of being refracted. [1913 Webster] 2. The change in the direction of ray of light, heat, or the like, when it enters obliquely a medium of a… …
132Half-tone — (h[aum]f t[=o]n ), a. Having, consisting of, or pertaining to, half tones; specif. (Photo engraving), pertaining to or designating plates, processes, or the pictures made by them, in which gradation of tone in the photograph is reproduced by a… …
