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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.
Measuring the slope angle of a tape or chain during distance measurement. Measuring the height of a building, tree, or other feature using a vertical angle and a distance (determined by taping or pacing), using trigonometry. Measuring the angle of drilling in well logging. Measuring the list of a ship in still water and the roll in rough water.
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 ...
Let the measure of the smallest main-scale reading, that is the distance between two consecutive graduations (also called its pitch) be S, and the distance between two consecutive vernier scale graduations be V, such that the length of (n − 1) main-scale divisions is equal to n vernier-scale divisions. Then
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.
Third-angle projection: In this type of projection, the object is imagined to be in the third quadrant. Again, as the observer is normally supposed to look from the right side of the quadrant to obtain the front view, in this method, the projection plane comes in between the observer and the object.
Jacob's staff in the Museo Galileo, Florence Measuring the height of a star with a Jacob's staff. The term Jacob's staff is used to refer to several things, also known as cross-staff, a ballastella, a fore-staff, a ballestilla, or a balestilha. In its most basic form, a Jacob's staff is a stick or pole with length markings; most staffs are much ...
New York (Essex County) Mt. Marcy: an 1892 USGS quadrangle map (or topographic sheet) of the Mount Marcy area of the Adirondacks in New York State from the first decades of the United States Geological Survey.