The Lady Knox Geyser is a geyser

Geyser

A geyser is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapour phase . The word geyser comes from Geysir, the name of an erupting spring at Haukadalur, Iceland; that name, in turn, comes from the Icelandic verb geysa, "to gush", the verb...

 in the Wai-o-Tapu

Wai-O-Tapu

Wai-O-Tapu is an active geothermal area at the southern end of the Okataina Volcanic Centre, just north of the Reporoa caldera, in New Zealand's Taupo Volcanic Zone. The area has many hot springs noted for their colourful appearance, in addition to the Lady Knox Geyser...

 area of the Taupo Volcanic Zone

Taupo Volcanic Zone

The Taupo Volcanic Zone is a highly active volcanic V shaped area in the North Island of New Zealand that is spreading east -west at the rate of about 8mm per year...

 in New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. It is named after Lady Constance Knox

Lady Constance Gaskell

Lady Constance Harriet Stuart Gaskell née Knox DCVO was a Woman of the Bedchamber to Queen Mary from 1937–53 and Lady-in-Waiting to Princess Marina, Duchess of Kent from 1953–60....

, the second daughter of Uchter Knox

Uchter Knox, 5th Earl of Ranfurly

Uchter John Mark Knox, 5th Earl of Ranfurly GCMG, PC was a British politician and colonial governor. He was Governor-General of New Zealand from 1897 to 1904.-Early life:...

, 15th Governor of New Zealand. The geyser is induced to erupt daily at 10:15am by dropping a surfactant

Surfactant

Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...

 into the opening of the vent. Eruptions produce a jet of water reaching up to 20m and can last for over an hour., depending on the weather

Weather

Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...

. The visible spout is made of rocks placed around the base of the spring to enhance the eruption; over the years silica from the eruptions has built up to give a white cone-shaped appearance.

Because the geyser was discovered early in the 20th century, it has no Māori

Maori language

Māori or te reo Māori , commonly te reo , is the language of the indigenous population of New Zealand, the Māori. It has the status of an official language in New Zealand...

name, unlike almost every other thermal feature in the region.

Eruption

The geyser has two water chambers, one lower, hot one and one upper, cold one. The upper chamber cools due to a larger opening to the outside. The lower one heats up due to the volcanic activity below. When soap is thrown into the upper water chamber, the lowered surface tension of the water allows it to mix with the hotter water below, causing the eruption.

Discovery

In 1901 the first open prison in New Zealand was established at Waiotapu, its object to accommodate some of the better behaved prisoners from around the jails of the Rotorua Lakes District.

It was a gang of those prisoners who first discovered the clearing in which the geyser is situated and that the spring could be made to erupt by adding soap, discovered when they first added soap to the hot water to wash their clothes.