Mural instrument
（重定向自Mural quadrant）
![Tycho Brahe's mural quadrant](/Images/godic/202501/28/Tycho_Brahes_stora_murkvadrant,_Nordisk_Familjebok2635.jpg")
![Mural quadrant constructed as a frame mounted on a wall. This instrument was made by John Bird in 1773 and is in the Museum of the History of Science, University of Oxford.](/Images/godic/202501/28/Mural_Quadrant_-_by_John_Bird_-_London_17732635.jpg")
![A Bird Mural Quadrant was for many years the main instrument of the Mannheim Observatory, shown here installed](/Images/godic/202501/28/BirdQuadrant2635.jpg")
![Ulugh Beg's mural sextant, constructed in Samarkand, Uzbekistan during the 15th century.](/Images/godic/202501/28/Ulugh_Beg_observatory2635.JPG")
A mural instrument is an angle measuring device mounted on or built into a wall. For astronomical purposes, these walls were oriented so they lie precisely on the meridian. A mural instrument that measured angles from 0 to 90 degrees was called a mural quadrant.