Halley's Meridian Line -- Royal Observatory, Greenwich, London, UK
N 51° 28.673 W 000° 00.088
30U E 708215 N 5707233
The historic marker pertaining to the Meridian Line determined by Astronomer Royal Edmond Halley in 1725
Waymark Code: WMT41F
Location: London, United Kingdom
Date Posted: 09/21/2016
Views: 6
One of several historical meridian lines surveyed by Astronomers Royal before 1884 (when the Prime Meridian was determined), Halley's Meridian line is marked on the inside and outside of the Royal Observatory at Greenwich near the Prime Meridian.
A nearby historical plaque reads as follows:
"HALLEY'S MERIDIAN LINE
Edmund Halley, the second Astronomer Royal, measured the height of stars above the horizon in time to their passage (or ‘transit’) over the meridian marked by the crosshairs in his telescope with an accurate pendulum clock. Astronomers opened hatches and the roof to observe the stars, with one of the most important observations being the Sun at solar noon.
Edmund Halley's meridian line of 1725 is shown on the wall to your right.
[drawing]
Halley use a large-scale mural quadrant like this (inside the building ahead of you) to provide accurate transit measurements."
Type of Historic Marker: Interpretive sign
Historical Marker Issuing Authority: Royal Museums Greenwich
Age/Event Date: 01/01/1725
Related Website: [Web Link]
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