Re: [tz] St Andrews meridian in the 17th century

On 2014-10-06 05:16, Tony Finch wrote:

Dunno how they got 200 years from the difference between 1673 (Gregory's St Andrews meridian) and 1721 (Halley's transit circle) or 1750 (the Bradley meridian, used for the Ordnance Survey).

Quote was: "almost 200 years before the Greenwich Meridian was established and arbitrarily adopted as the world’s official prime meridian." Airy transit circle installed 1851 and defined as Prime Meridian at International Meridian Conference in 1884. -- Take care. Thanks, Brian Inglis