Mapping the stars: Mural quadrant

Essential information

Royal Observatory, Meridian Line and Historic Royal Observatory, Flamsteed House, Time & Longitude gallery

Get your bearings with the remains of one of our greatest ever instrument maker's mural quadrant.

A mural quadrant is a telescope mounted on a quarter circle frame which is then mounted on a wall aligned north-south so that the two sides run vertical and horizontal.

These are the unfinished remains of a 5ft wall or mural quadrant made by Flamsteed's instrument maker, Abraham Sharp. Though never used or intended for use at Greenwich this is one of the few surviving examples of the work of the Observatory's 17th-18th century instrument maker, Abraham Sharp. 

The telescope is pivoted at what would be the centre of the circle while the circle's circumference carries a scale from 0 to 90 degrees. This allows the observer to measure the angular height of the star he or she is observing. The telescope here is missing or perhaps never made.

The frame is made of oak, strengthened with iron. The central radial bar was missing in 1865 and replaced at that time and the vertical oak was reduced by 2 inches in 1960 because of woodworm. The scale around the circumference of the frame is engraved on an arc of sheet brass. 

Artist/Maker Sharp, Abraham
Credit National Maritime Museum, Greenwich, London. Presented to the Royal Observatory in 1865 by Rev. N. S. Heineken
Date Made circa 1790