PRESENTATION n.
The particular position of the child during labor relatively to the passage though which it is to be brought forth; -- specifically designated by the part which first appears at the mouth of the uterus; as, a breech presentation. Presentation copy, a copy of a book, engraving, etc., presented to some one by the author…
PRISM n.
g them different refracting angles, so that, when placed together so as to have opposite relative positions, a ray of light passed through them is refracted or bent into a new position, but is free from color. -- Nicol's prism, Nicol prism. Etym: [So called from Wm. Nicol, of Edinburgh, who first proposed it.] (Opt.)…
QUANTITY n.
r by its momentum under a given velocity. -- Quantity of motion (Mech.), in a body, the relative amount of its motion, as measured by its momentum, varying as the product of mass and velocity. -- Known quantities (Math.), quantities whose values are given. -- Unknown quantities (Math.), quantities whose values are s…
REFRACTION n.
t. -- Differential refraction (Astron.), the change of the apparent place of one object relative to a second object near it, due to refraction; also, the correction required to be made to the observed relative places of the two bodies. -- Double refraction (Opt.), the refraction of light in two directions, which prod…