A weather vane, wind vane, or weathercock is an instrument for showing the direction of the wind. They are typically used as an architectural ornament to the highest point of a building.
Although partly functional, weather 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.
The word ‘vane’ comes from the Old English word fana meaning ‘flag’.
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, the frieze was adorned with the eight wind deities. The eight metre high structure also featured sundials, and a water clock inside dates from around 50 BC.
Pope Gregory I said that the cock (rooster) “was the most suitable emblem of Christianity”, being “the emblem of St Peter”. Some say that it was as a result of this that the cock began gradually to be used as a weather vane on church steeples, and some add that in the 9th century Pope Nicholas I ordered the figure to be placed on every church steeple. and it is known that Pope Leo IV did have it placed on the Old St. Peter’s Basilica or old Constantinian basilica even before Nicholas I was Pope. Alternative theories about the origin of weathercocks on church steeples are that it was an emblem of the vigilance of the clergy calling the people to prayer, that it was derived from the Goths and is only possibly a Christian symbol, and that it is an emblem of the sun.
As it were, Pope Nicholas I did in fact decree in the 9th century that all churches must show the symbol of a cock on its dome or steeple, as a symbol of Jesus’ prophecy of Peter’s betrayal (Luke 22:34), that Peter would deny him three times before the rooster crowed on the morning following the Last Supper. Many churches started using this symbol on its weathervanes. The weathervanes has North, East, South, West, Or Opposite. In the Bayeux Tapestry of the 1070s, originally of the Bayeux Cathedral (Cathédrale Notre-Dame de Bayeux) and now exhibited at Musée de la Tapisserie de Bayeux in Bayeux, Normandy, there is a depiction of a man installing a cock on Westminster Abbey. Other sources cited above say the custom had begun more than two centuries earlier. In fact, the oldest weather vane with the shape of a rooster existing at the world is the Gallo di Ramperto, made in 820 and now preserved in the Museo di Santa Giulia in Brescia, Lombardy.
Early weather vanes had very ornamental pointers, but modern wind vanes are usually simple arrows that dispense with the directionals because the instrument is connected to a remote reading station. An early example of this was installed in the Royal Navy’s Admiralty building in London – the vane on the roof was mechanically linked to a large dial in the boardroom so senior officers were always aware of the wind direction when they met.
Modern aerovanes combine the directional vane with an anemometer (a device for measuring wind speed). Co-locating both instruments allows them to use the same axis (a vertical rod) and provides a coordinated readout. Read more