A mural instrument is an angle measuring instrument 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.[1]
The mural quadrant has been called the "quintessential instrument" of 18th century (i.e. 1700s) observatories.[2] It rose to prominence in the field of positional astronomy at this time.[2]
- ^ Robert Grant, History of Physical Astronomy from The Earliest Ages to the Nineteenth Century (1852) pp. 483-484.
- ^ a b "2002JHA....33..373T Page 373". adsabs.harvard.edu. Retrieved 2019-11-14.