Bidston Observatory, Bidston Hill, Bidston, Merseyside
This observatory was built in 1866 under the supervision of the first director, John Hartup. He also designed the building. It is important architecturally as a specialised construction built to minimise vibrations. The basement area was surrounded by a 'moat' to reduce vibration. There was a great central pier to stabilise the transit telescope (now removed). One of its original functions was to set the exact time. Up to 1969, at exactly 13:00 each day, the River Mersey One O'Clock Gun would be fired electrically from the Observatory. This allowed ships to set their chronometers (used for navigation) before departing on a long voyage. In 1929 the observatory was amalgamated with the Tidal Institute under the direction of Joseph Proudman and Arthur Doodson. They carried out pioneering work on tidal predictions and their work led to reliable tidal predictions worldwide. It was of national importance during WW2 and predicted the tides for the D-day landings. The mechanical calculator devised by Doodson for this work was also important in the development of the digital computer.