Quadrant (instrument)
Its earliest recorded usage was in ancient India in Rigvedic times by Rishi Atri to observe a solar eclipse.
The term quadrant, meaning one fourth, refers to the fact that early versions of the instrument were derived from astrolabes.
During Rigvedic times in ancient India, quadrants called 'Tureeyam's were used to measure the extent of a great solar eclipse.
He described a "plinth" that could measure the altitude of the noon sun by projecting the shadow of a peg on a graduated arc of 90 degrees.
Ptolemy's version was a derivative of the astrolabe and the purpose of this rudimentary device was to measure the meridian angle of the sun.
The first of these, the sine quadrant, was invented by Muhammad ibn Musa al-Khwarizmi in the 9th century at the House of Wisdom in Baghdad.
In the 13th century Jewish astronomer Jacob ben Machir ibn Tibbon was crucial in further developing the quadrant.
[7] He was a skilled astronomer and wrote several volumes on the topic, including an influential book detailing how to build and use an improved version of the quadrant.
Tibbon's Hebrew manuscripts were translated into Latin and improved upon by Danish scholar Peter Nightingale several years later.
Tibbon's work had a far reach and influenced Copernicus, Christopher Clavius and Erasmus Reinhold; and his manuscript was referenced in Dante's Divine Comedy.
This application of quadrants is generally attributed to Arab sailors who traded along the east coast of Africa and often travelled out of sight of land.
Large frame quadrants were used for astronomical measurements, notably determining the altitude of celestial objects.
Navy: Used to gauge elevation on ships cannon, the quadrant had to be placed on each gun's trunnion in order to judge range, after the loading.
In more modern applications, the quadrant is attached to the trunnion ring or of a large naval gun to align it to benchmarks welded to the ship's deck.
In large, unused spaces on the instrument, a sigil or badge would often be added to denote the ownership by an important person or the allegiance of the owner.
