The photograph of the Half Moon Battery was taken in the 1840s by David Octavius Hill and Robert Adamson. In June 1861 the twenty four pounder standing to the left of the flagpole was used to fire the daily time signal. This time gun failed to fire due to a faulty friction tube. The twenty four pounder was replaced by a twelve pounder from the Argyle Battery.
The work on the observatory is taking longer than expected. The buildings and compound should be open to the public in eight weeks time. image credit National Galleries Scotland.