From 1885, Hong Kong Time was determined by astronomical observations at the Hong Kong Observatory using a 6-inch equatorial mount and a 3-inch Transit Circle. The time was announced to the general public, particularly mariners, by dropping a 6-feet diameter time ball from a mast exactly at 13:00 daily in front the Marine Police Headquarters Compound, where it is visible from the Victoria Harbour. In January 1908, the time ball was relocated to the hill of Blackhead Point where it had even higher visibility. With the rise of radio broadcast and the launching of Radio Hong Kong in 1922, the importance of the time ball decreased. It was decommissioned on 30 June 1933.