A closed figure having arcs of three great circles as sides.
Related Terms 
INFLUENCE DIAGRAM
[SYS ENG] A graphtheoretic representation of a decision, which may include four types of nodes (decision, chance, value, and deterministic), directed arcs between the nodes (which identify dependencies between them), a marginal or conditional probability distribution defined at each chance node, and a mathematical function associated with each of the other types of node.

ARCS
Admiralty Raster Chart Service electronic raster charts produced by the United Kingdom Hydrographic Office

STAR GLOBE
A small globe representing the celestial sphere, on which the apparent positions of the stars are indicated. It is usually provided with graduated arcs and a suitable mount for determining the approximate altitude and azimuth of the stars, to serve as a star finder. Star globes are more commonly used by the British than by Americans. Also called CELESTIAL GLOBE.

TIME DIAGRAM
A diagram in which the celestial equator appears as a circle, and celestial meridians and hour circles as radial lines; used to facilitate solution of time problems and others involving arcs of the celestial equator or angles at the pole, by indicating relations between various quantities involved. Conventionally the relation ships are given as viewed from a point over the south pole westward direction being counterclockwise. Also called DIAGRAM ON THE PLANE OF THE CELESTIAL EQUATOR, DIAGRAM ON THE PLANE OF THE EQUINOCTIAL.

TRIANGLE
A closed figure having three sides. The triangle is plane, spherical, or curvilinear as the sides are straight lines, arcs of great circles, or curves, respectively.

ARC PROCESS
A former process that used electric arcs for fixation (oxidation) of atmospheric nitrogen to manufacture nitric acid.

CRESCENT BEAM
A beam bounded by arcs having different centers of curvature, with the central section the largest.

GARTER SPRINGA closed ring formed of helically wound wire. Such springs used to secure carbon ring packing segments in a turbogenerator gland. 
PLUG VALVE
A valve fitted with a plug that has a hole through which fluid flows and that is rotatable through 90 for operation in the open or closed position. Also known as plug cock.

PENSTOCK
1. A valve or sluice gate for regulating water or sewage flow. 2. A closed water conduit controlled by valves and located between the intake and the turbine in a hydroelectric plant.
