PORPHYRY n.
A term used somewhat loosely to designate a rock consisting of a fine-grained base (usually feldspathic) through which crystals, as of feldspar or quartz, are disseminated. There are red, purple, and green varieties, which are highly esteemed as marbles. Porphyry shell (Zoöl.), a handsome marine gastropod shell (Oliva…
PRESENTATION n.
g 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 or artist, as a token of regard.…
REVOLUTION n.
or orbit, until it returns to the same point again, or to a point relatively the same; -- designated as the annual, anomalistic, nodical, sidereal, or tropical revolution, according as the point of return or completion has a fixed relation to the year, the anomaly, the nodes, the stars, or the tropics; as, the revoluti…