Australia's Great Artesian Basin is surrounded by numerous mound springs. In the dry outback these springs are a precious supply of fresh water. In 1858 Emerald Spring was the first of these to be discovered. It was named for the green plants which surrounded it.

Benjamin Babbage was the leader of a large South Australian Government expedition sent to explore the region to the north of Spencer Gulf. He was searching for a way past what appeared to be a horseshoe-shaped salt lake. This had barred South Australian progress to the north for nearly 17 years, since it was first described by Edward Eyre.

In addition to his sketch of Emerald Spring, Benjamin Babbage made notes regarding it. In his sketch book he wrote:

A hot spring on the west side of Lake Gregorydiscovered by me on -- Oct: the mound in the centre of the sketch is of a marly sand* about 20 feet above the clay from below. The top is round the edge covered by reeds and forms the rim of the basin about 5 feet deep and 40 yards diam[eter]: the bottom is covered with rushes out of which at all points bubbles up hot water at about 90 degrees. The rate per 24 hours of this spring is about 175,000 gallons.

What Babbage did not record in his sketch book, but included in his report to the South Australian Government, was his method of testing the spring's temperature. As he did not have a suitable thermometer, Babbage tested the water with his arm. He pushed down into the underlying sand and found it 'so hot as to be scarcely bearable.' however the expedition's horses readily drank the fresh water. The explorers used it to make tea.

The Emerald Spring (now officially known as Emerald Springs) which Babbage discovered, was the first of many found in an arc south of Lake Eyre. These mound springs were vital to northern exploration. Their discovery paved the way for pastoralism in the north of South Australia.

*marly sand is a mixture of clay, sand, and limestone, usually containing shell fragments.

Babbage, Benjamin Herschel, 1815-1878

State Library of South Australia: Mortlock Wing. Taking it to the edge August 2004-