Puddling technology was developed entirely in Victoria from the early 1850s. The need for these machines arose due to the enormous amounts of clay soil in the region which needed to be broken up to retrieve the gold.
Earth Resources offers the following concise description of a puddling machine:
Puddling machines were pioneered on the Victorian goldfields in 1854 as an affordable means of processing gold-bearing clay on a large scale.
A horse dragged a harrow repeatedly through a circular, barklined trough full of clay and water, 'puddling' the mixture into a thin sludge. Any gold freed from the lumpy clay would sink, remaining behind on the bottom of the trough after the watery sludge was drained off.
A clean-up of the residue, using tin-dish or cradle, would bring the gold finally to light.
Photograph of a gold puddling machine used in Victorian gold mining.
Image source: Federation University Australia E.J. Barker Library (top floor) Mount Helen Victoria