Bradley's Meridian Line -- Royal Observatory, Greenwich, London, UK
N 51° 28.673 W 000° 00.088
30U E 708215 N 5707233
The Meridian Line determined by Astronomer Royal James Bradley in 1750
Waymark Code: WMT41J
Location: London, United Kingdom
Date Posted: 09/21/2016
Views: 5
One of several historical meridian lines surveyed by Astronomers Royal before 1884 (when the Prime Meridian was determined), Bradley's Meridian line is marked on the inside and outside of the Royal Observatory at Greenwich.
A nearby historical plaque reads as follows:
"BRADLEY’S MERIDIAN LINE
James Bradley, third astronomer Royal, observed with improved accuracy using the telescope (purchased in 1749) that first defined this line in 1750. Owing to the unequal length of solar days, astronomers measure the time using distant stars. Stars cross the meridian of an observer around every 23 hours 56 min. Astronomers clocks run slightly faster than normal clocks to show sidereal (star) time.
You are now standing James Bradley's Meridian line(1750). This is still the reference point for ordnance survey maps today.
Bradley preferred using this transit telescope (inside the building ahead of you) as it produced a wider range of measurements."
Type of Historic Marker: Interpretive sign
Historical Marker Issuing Authority: Royal Museums Greenwich
Age/Event Date: 01/01/1750
Related Website: [Web Link]
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