Weather vane

A weather vane, wind vane, or weathercock is an instrument used for showing the direction of the wind. It is typically used as an architectural ornament to the highest point of a building. The word vane comes from the Old English word fana meaning 'flag'.The Han 'Ling Tai' (Observatory Platform) was eight li north-west of Chang'an. It was called 'Ling Tai' because it was originally intended for observations of the Yin and the Yang and the changes occurring in the celestial bodies, but in the Han it began to be called Qing Tai. Guo Yuansheng, in his Shu Zheng Ji (Records of Military Expeditions), says that south of the palaces there was a Ling Tai, fifteen ren (120 feet) high,upon the top of which was the armillary sphere made by Zhang Heng. Also there was a wind-indicating bronze bird (xiang feng tong wu), which was moved by the wind; and it was said that the bird moved when a 1000-li wind wasblowing. There was also a bronze gnomon 8 feet high, with a 13 feet long and 1 foot 2 inches broad. According to an inscription, this was set up in the 4th year of the Taichu reign-period (101 BC). A weather vane, wind vane, or weathercock is an instrument used for showing the direction of the wind. It is typically used as an architectural ornament to the highest point of a building. The word vane comes from the Old English word fana meaning 'flag'. Although partly functional, wind vanes are generally decorative, often featuring the traditional cockerel design with letters indicating the points of the compass. Other common motifs include ships, arrows and horses. Not all weather vanes have pointers. When the wind is sufficiently strong, the head of the arrow or cockerel (or equivalent depending on the chosen design) will indicate the direction from which the wind is blowing. The weather vane was independently invented in ancient China and Greece around the same time during the 2nd century BCE. The earliest written reference to a weather vane appears in the Huainanzi, and a weather vane was fitted on top of the Tower of the Winds in Athens. The oldest textual reference to a weather vane comes from the ancient Chinese text Huainanzi dating from around 139 BC, which describes a 'wind-observing fan' (hou feng shan, 侯風扇). The Tower of the Winds on the ancient Greek agora in Athens once bore on its roof a wind vane in the form of a bronze Triton holding a rod in his outstretched hand, rotating as the wind changed direction. Below this was a frieze adorned with the eight Greek wind deities. The eight-metre-high structure also featured sundials, and a water clock inside. It dates from around 50 BC. Military documents from the Three Kingdoms period of China (220–280) refer to the weather vane as 'five ounces' (wu liang, 五兩), named after the weight of its materials. By the 3rd century, Chinese weather vanes were shaped like birds and took the name of 'wind-indicating bird' (xiang feng wu, 相風烏). The Sanfu huangtu (三輔黃圖), a 3rd-century book written by Miao Changyan about the palaces at Chang'an, describes a bird-shaped wind vane situated on a tower roof, which was possibly also an anemometer: The oldest surviving weather vane with the shape of a rooster is the Gallo di Ramperto, made in 820 AD and now preserved in the Museo di Santa Giulia in Brescia, Lombardy. Pope Leo IV had a cock placed on the Old St. Peter's Basilica or old Constantinian basilica. Pope Gregory I said that the cock (rooster) 'was the most suitable emblem of Christianity', being 'the emblem of St Peter', a reference to Luke 22:34 in which Jesus predicts that Peter will deny him three times before the rooster crows. As a result of this, the cock gradually began to be used as a weather vane on church steeples, and in the 9th century Pope Nicholas I ordered the figure to be placed on every church steeple.