ANGLE OF UNCERTAINTY

The horizontal angle of the region of indefinite characteristic near the boundaries of a sector of a sector light. Also called ARC OF UNCERTAINTY.

angle_of_uncertainty angle horizontal arc characteristic sector

Related Terms

PLUNGE

To set the horizontal cross hair of a theodolite in the direction of a grade when establishing a grade between two points of known level.

plunge horizontal grade direction set two cross_hair

PENDULUM SCALE

Weight-measurement device in which the load is balanced by the movement of one or more pendulums from vertical (zero weight) to horizontal (maximum weight).

pendulum_scale horizontal load vertical device movement

PENDULUM LEVEL

A leveling instrument in which the line of sight is automatically kept horizontal by a built-in pendulum device (such as a horizontal arm and a plumb line at right angles to the arm).

pendulum_level horizontal plumb_line sight line line_of_sight leveling right plumb instrument device leveling_instrument

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity; the angular deflection of the plate is a function of the wind speed; this instrument is not used for station measurements because of the false reading which results when the frequency of the wind gusts and the natural frequency of the swinging plate coincide.

pendulum_anemometer plate deflection horizontal station plane wind natural_frequency axis frequency anemometer center swing

OPTICAL BENCH

A rigid horizontal bar or track for holding optical devices in experiments; it allows device positions to be changed and adjusted easily.

optical_bench horizontal device bar track

NEEDLE DAM

A barrier made of horizontal bars across a pass through a dam or of planks that can be removed in case of flooding.

needle_dam barrier horizontal case planks can pass dam

MOVABLE BRIDGE

A bridge in which either the horizontal or vertical alignment can be readily changed to permit the passage of traffic beneath it. Often called drawbridge (an anachronism).

movable_bridge traffic horizontal bridge passage alignment vertical can drawbridge

MAXIMUM GRADABILITY

Steepest slope a vehicle can negotiate in low gear; usually expressed in precentage of slope, namely, the ratio between the vertical rise and the horizontal distance traveled; sometimes expressed by the angle between the slope and the horizontal.

maximum_gradability horizontal ratio vertical can low distance angle vehicle rise slope

LONGITUDINAL STABILITY

The ability of a ship or aircraft to recover a horizontal position after a vertical motion of its ends about a horizontal axis perpendicular to the centerline.

longitudinal_stability horizontal perpendicular axis ship vertical motion aircraft position

LONGITUDINAL DRUM BOILER

A boiler in which the axis of the horizontal drum is parallel to the tubes, both lying in the same plane.

longitudinal_drum_boiler boiler horizontal parallel axis drum