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A quadrant is an instrument used to measure angles up to 90°. Different versions of this instrument could be used to calculate various readings, such as longitude , latitude , and time of day . Its earliest recorded usage was in ancient India in Rigvedic times by Rishi Atri to observe a solar eclipse.
Reflecting quadrant derives from the instrument using mirrors to reflect the path of light to the observer and, in doing so, doubles the angle measured. This allows the instrument to use a one-eighth of a turn to measure a quarter- turn or quadrant .
The frame of a sextant is in the shape of a sector which is approximately 1 ⁄ 6 of a circle (60°), [2] hence its name (sextāns, sextantis is the Latin word for "one sixth"). "). Both smaller and larger instruments are (or were) in use: the octant, quintant (or pentant) and the (doubly reflecting) quadrant [3] span sectors of approximately 1 ⁄ 8 of a circle (45°), 1 ⁄ 5 of a circle (72 ...
Many mural quadrants were constructed, giving the observer the ability to measure a 90° range of elevation. There were also mural sextants that read 60°. Mural quadrants of the 17th century were noted for their expense, with Flamsteed's 1689 quadrant costing £120 (equivalent to £27,488 in 2023), and Edmund Halley's 1725 quadrant which cost ...
A simple alidade for use with a ceiling projector. An alidade (/ ˈ æ. l ɪ. d eɪ d /) (archaic forms include alhidade, alhidad, alidad) [citation needed] or a turning board is a device that allows one to sight a distant object and use the line of sight to perform a task.
The area of the shape is proportional to the number of turns through which the measuring wheel rotates. The polar planimeter is restricted by design to measuring areas within limits determined by its size and geometry. However, the linear type has no restriction in one dimension, because it can roll.
An octant, also called "reflecting quadrant", is a measuring instrument used primarily in navigation. It is a type of reflecting instrument that uses mirrors to reflect the path of light to the observer and, in doing so, doubles the angle measured. This allows the instrument to use a one-eighth circle arc to measure a quarter circle or quadrant.
The median is the most trimmed statistic (nominally 50%), as it discards all but the most central data, and equals the fully trimmed mean – or indeed fully trimmed mid-range, or (for odd-size data sets) the fully trimmed maximum or minimum. Likewise, no degree of trimming has any effect on the median – a trimmed median is the median ...