The Airy Transit Circle was designed by George Biddell Airy, and came into use 150 years ago. The first observation was taken on 4 January 1851, three days later than Airy had intended due to the English weather. The circle remained in continual use until 1938, and the last ever observation was taken in 1954.
Mounted in the Transit Circle Room,defining the Greenwich Meridian since 4 January 1851.Makers: Ransomes & May of Ipswich (engineering)Troughton & Simms of London (optical and instrumental)to the design of G. B. Airy. Lens: 8.1 inch aperture objective glass Focal Length: 11 feet 7 inches Magnification: 195 (180 for the Sun).
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