page_title: Mural instrument
section_title: Famous mural instruments
hierarchical_section_title: Mural instrument / Famous mural instruments
caption_attribution_description: Observatory built by Ulugh Beg in Samarkand, the Timurid Empire (15th century) — present day Uzbekistan
context_page_description: 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. They were utilized as astronomical devices in ancient Egypt and ancient Greece. Edmond Halley, due to the lack of an assistant and only one vertical wire in his transit, confined himself to the use of a mural quadrant built by George Graham after its erection in 1725 at the Royal Observatory, Greenwich. Bradley's first observation with that quadrant was made on 15 June 1742.
  The mural quadrant has been called the "quintessential instrument" of 18th century observatories. It rose to prominence in the field of positional astronomy at this time.
context_section_description: A mural sextant was constructed in Ray, Iran, by Abu-Mahmud al-Khujandi in 994.
  Ulugh Beg constructed the "Fakhri Sextant" in Samarkand that had a radius of 40 meters.  Seen in the image on the right, the arc was finely constructed with a staircase on either side to provide access for the assistants who performed the measurements.
  Tycho Brahe's mural quadrant in Uraniborg at Hven.
  The mural quadrant at the Greenwich Observatory.
  Ptolemy's mural quadrant at Alexandria.  This instrument is also referred to as a plinth.
  The obsolete constellation Quadrans Muralis represents a mural quadrant.
  The mural quadrant at the Mannheim Observatory.  This is another of John Bird's instruments.
caption: Ulugh Beg's mural sextant, constructed in Samarkand, Uzbekistan during the 15th century.
exif: {"Image ImageDescription": "OLYMPUS DIGITAL CAMERA", "Image Make": "OLYMPUS OPTICAL CO.,LTD", "Image Model": "C4100Z,C4000Z", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "v575u-77", "Image DateTime": "0000:00:00 00:00:00", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "284", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "4084", "Thumbnail JPEGInterchangeFormatLength": "4056", "EXIF ExposureTime": "5/8", "EXIF FNumber": "14/5", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "0000:00:00 00:00:00", "EXIF DateTimeDigitized": "0000:00:00 00:00:00", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "2", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "3", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "34/5", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2288", "EXIF ExifImageLength": "1712", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "1002", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "Low gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}