If the river Rhone is the backbone of Geneva, then the lakefront with its famous water jet is probably its best-known face to the outside world. Each morning at 10 o’clock a 16cm diameter jet spews out water at some 200km an hour, to form a dazzling plume of white foam reaching an impressive average of 140 metres in height - as high as Kheops’ Great Pyramid.
A symbol of the City of Geneva since its relocation to the quayside in 1891, although originally almost a matter of chance, its invention also bears witness to the ingenuity of the city’s engineers. Until the late 19th century, water was the city’s main form of power and the key driver of progress. The city had experienced a tremendous increase in population, from 64’000 inhabitants in 1850 to over 100’000 in 1890.
The need for water was therefore imperative to ensure that progress continued, and a hydro-electric plant was commissioned at the Coulouvrenière in Geneva in 1886, which operated until 1990, with the aim of harnessing the power of the Rhône to provide a power supply for the artisans of Geneva. However when these same artisan watchmakers shut up shop in the evening, it created excess pressure which the machine operators then had to rush to the pumps to rectify. The idea was then born of creating a second outlet through a safety valve which could control the pressure by letting air escape into the water under pressure The first jet of water 30 meters high was created. It was located at the tip of the furthest wing of the Coulouvrenière hydraulic power factory. In July 1891 the Administrative Council of the City of Geneva decided to promote it to the rank of a tourist attraction and move it into the quayside in celebration of the Federal Gymnastics Festival and the 600th anniversary of the Swiss Confederation, on which occasion it was operated for the first time.
The need for water was therefore imperative to ensure that progress continued, and a hydro-electric plant was commissioned at the Coulouvrenière in Geneva in 1886, which operated until 1990, with the aim of harnessing the power of the Rhône to provide a power supply for the artisans of Geneva. However when these same artisan watchmakers shut up shop in the evening, it created excess pressure which the machine operators then had to rush to the pumps to rectify. The idea was then born of creating a second outlet through a safety valve which could control the pressure by letting air escape into the water under pressure The first jet of water 30 meters high was created. It was located at the tip of the furthest wing of the Coulouvrenière hydraulic power factory. In July 1891 the Administrative Council of the City of Geneva decided to promote it to the rank of a tourist attraction and move it into the quayside in celebration of the Federal Gymnastics Festival and the 600th anniversary of the Swiss Confederation, on which occasion it was operated for the first time.
Until 1951, the ‘Jet d’eau’ was connected to the drinking-water supply, but sending a cubic metre of water in the sky every two seconds is a big production. In order to control all aspects of its operation, an independent, partially-submerged pumping station using lake water was built in the harbour. The particularly innovative features of its design lie in the ingenious engineering of the technical installation and in the construction of its double helix nozzle which, by mixing the flow of water with millions of air bubbles, enables the spout to reach its remarkable height and gives the jet its foamy white colour. It is now this same pumping station which provides the water jet with a pressure of 500 litres a second, sufficient to allow it to operate almost all year round. When the wind blows at more than 25 km per hour the pumps are halted to stop the water spout from dousing the neighbouring Quai Gustav Ador and its constant throng of pedestrians and cars, and also in winter when the temperature dips below 2 degrees, to prevent this famous landmark from being transformed into a giant snow cannon. As a result, the Jet d’eau is only turned on from 10 am to 11 pm in the summer months and from 3pm to 8 pm in winter.
For 300 Swiss francs an hour it can even be rented out - the local hockey club ‘Servette Hockey Club’ hired it and died the jet their team’s claret-colour when it reached the final this year, and during the Euro 2008 championships which were held jointly in Switzerland and Austria, this internationally-known icon was tantalisingly coiffed with a giant inflatable football for the entire duration…
Group visits of the machine room (before 10 am) can be arranged upon request from 1st April to 31st October, from the Geneva public utilities company, the SIG (www.sig-ge.ch)
Some technical details
Average height of the Jet: 140 meters
Output speed of water: 200 km / h
Flow: 500 litres / second
Two motor-pumps: a total power of 1000 kW
Flow rate each pump: 250 litres / second
Lighting Power: 9000 watts
Number of projectors: 12 with metal halide lamps
