A great circle of the celestial sphere through the zenith and nadir. Vertical circles are perpendicular to the horizon. The prime vertical circle or prime vertical passes through the east and west points of the horizon. The principal vertical circle passes through the north and south points of the horizon and coincides with the celestial meridian.


Related Terms

PISTON CORER

A steel tube which is driven into the sediment by a free fall and by lead attached to the upper end, and which is capable of recovering undistorted vertical sections of sediment.

PILASTER

A vertical rectangular architectural member that is structurally a pier and architecturally a column.

PETTIT TRUSS

A bridge truss in which the panel is subdivided by a short diagonal and a short vertical member, both intersecting the main diagonal at its midpoint.

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 SAW

A circular saw that swings in a vertical arc for crosscuts.

PANEL POINT

The point in a framed structure where a vertical or diagonal member and a chord intersect.

OMNIMETER

A theodolite with a microscope that can be used to observe vertical angular movement of the telescope.

NORMAL AXIS

The vertical axis of an aircraft or missile.

NONBEARING WALL

A wall that bears no vertical weight other than its own.

NIPHER SHIELD

A conically shaped, copper, rain-gage shield; used to prevent the formation of vertical wind eddies in the vicinity of the mouth of the gage, thereby making the rainfall catch a representative one.

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