What is that “crystal ball” on the table in the History Room and on the roof of the tower?

| February 24, 2014 | Reply

The “crystal ball” is not used to predict the future (although we wish it could do so). The crystal ball is actually a Campbell-Stokes sunshine recorder. This device was in use on the roof of the building for over 100 years. The sunshine recorder is essentially a magnifying glass that burns a track in a recording card when the sun is shining. The card is marked in hours, so we know during any day when the sun was shining and when it was cloudy. There is an essentially identical replacement device on the south side of the Observatory roof in daily use since replacing the original.

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