PARADE. An assembling of troops in due military order. Also, the open space where they parade or are paraded. The quarter-deck of a man-of-war is often termed the sovereign's parade.
PARALLACTIC ANGLE. The angle made at a star by arcs passing through the zenith and pole respectively.
PARALLAX. An apparent change in the position of an object, arising from a change of the observer's station, and which diminishes with the altitude of an object in the vertical circle. Its effect is greatest in the horizon, where it is termed the horizontal parallax, and vanishes entirely in the zenith. The positions of the planets and comets, as viewed from the surface of the earth, differ from those they would occupy if observed from its centre by the amount of parallax, the due application of which is an important element. The stars are so distant that their positions are the same from whatever part of the earth they are seen; but attempts have been made to detect the amount of variation in their places, when observed from opposite points of the earth's orbit, the minute result of which is termed the annual parallax; and the former effect, due to the observer's station on our globe, is called the diurnal parallax.
PARALLEL. A term for those lines that preserve an equal distance from each other. It is sometimes used instead of latitude, as, "Our orders were to cruise in the parallel of Madeira." More definitely, they are imaginary circles parallel with the equator, ninety in the northern, and ninety in the southern hemispheres.
PARALLEL-BAR. In the marine steam-engine, forms a connection with the pump-rods and studs along the centre line of the levers.
PARALLEL OF LATITUDE. Is a circle parallel to the equator passing through any place. Almucantar is the Arabic name.
PARALLELOGRAM. A right-lined quadrilateral figure, the opposite sides of which are parallel and equal.
PARALLELOPIPED. A prism or solid figure contained under six parallelograms, the opposite sides of which are equal and parallel.
PARALLELS. The trenches or lines made by a besieger parallel to the general defence of a place, for the purpose of connecting and supporting his several approaches.
PARALLEL SAILING. Sailing nearly on a given parallel of latitude.