CONTRAVALLATION
, Line of, in Fortification, is a trench, guarded with a parapet; being made by the besiegers, between them and the place besieged, to secure themselves on that side, and stop the sallies of the garrison. It is made without musket-shot of the town; sometimes going quite around it, and sometimes not, as occasion may require. The besiegers lie between the lines of circumvallation and contravallation: but it is now seldom used.
CONVERGING Curves. See Curve.
Converging, or Convergent Lines, in Geometry, are those that continually approximate, or whose distance becomes continually less and less the farther they are continued, till they meet: in opposition to divergent lines, whose distance becomes continually greater.
Lines that converge the one way, diverge the other.
Converging Rays, in Optics, are such as incline towards one another in their passage, and in Dioptrics, are those rays which, in their passage out of one medium into another of a different density, are refracted towards one another; so that, if far enough continued, they will meet in a point or focus.
Converging Series, a series of terms or quantities, that always decrease the farther they proceed, or which tend to a certain magnitude or limit: in opposition to diverging series, or such as become larger and larger continually. See Series.
CONVERSE. A proposition is said to be the converse of another, when, after drawing a conclusion from something first supposed, we return again, and, making a supposition of what had before been concluded, draw from thence as a conclusion what before was made the | supposition. Thus, when it is supposed that the two sides of a triangle are equal, and thence demonstrate or conclude that the two angles opposite to those fides are equal also; then the converse is to suppose that the two angles of a triangle are equal, and thence to prove or conclude that the sides opposite to those angles are also equal.
Converse Direction, in Astrology, is used in opposition to direct direction; that is, by the latter the promoter is carried to the significator, according to the order of the signs: whereas by the other it is carried from east to west, contrary to the order of the signs.
