Lady Knox (eng. Lady Knox Geyser) is a geyser located in the Wai-O-Tapu region, the Taupo volcanic zone of the North island of New Zealand. It is named after Lady Constance Knox, second daughter of Actor Knox, 5th Earl of Ranfurly, 15th Governor-General of New Zealand. An eruption of a geyser is caused artificially (by pouring a soap solution into the mouth of the geyser) every day at 10: 15 am. During an eruption that lasts about an hour, the geyser emits a jet of water up to 20 meters high depending on the weather. the Visible part consists of stone formations located at the base of the source. Silicon, which has accumulated over many years during eruptions, forms a light cone-shaped top of the geyser.
Since the geyser was only discovered in the early twentieth century, it does not have a name in the Maori language, like other geysers and springs in the region.
Inside the Lady Knox geyser, there are two water chambers: the lower one with hot water, and the upper one with cold water. The water in the upper chamber is cooled by interacting with the air outside; and the high temperature in the lower chamber is maintained by volcanic activity. Adding soap to the mouth of the geyser causes the water from the two chambers to mix (since the friction of the water surface of the two chambers is reduced), and an eruption occurs.
In 1901, New Zealand’s first open prison was built in the Wai-O-Tapu area, and prisoners of good behavior were transferred to It from other prisons located in the lake Rotorua area.
It was the prisoners of this prison who discovered this geyser, as well as the ability to cause an eruption by adding soap. The artificial eruption was made by accident when people first decided to wash their clothes in hot spring water.