Local people in Hong Kong were warned of the hazardous wind conditions associated with tropical cyclones by means of a typhoon gun as early as August 1884. At the time, the typhoon gun was placed at the foot of the mast in front of the Police Barracks at Tsim Sha Tsui facing Victoria Harbour. It was fired once whenever a strong gale of wind was expected. It was fired twice whenever the wind was expected to blow with typhoon force and fired again if possible when the wind was likely to suddenly shift around. The first typhoon gun was fired on 21 August 1884 although no gale-force wind was recorded at the Observatory or Gap Rock, an island about 40 kilometres to the southwest of Hong Kong. However, it was noted that the typhoon gun also performed its double duty as the mail gun in announcing the arrival of postal services from London at the time, causing local vessels and people to seek shelter from a non-existent typhoon.