The official survey of the 29ºS parallel was conducted by John Cameron (NSW) and George Watson (Qld) between 1879 and 1881.
“That we have been inspected very much of late will be evident from the following lines. First of all the Inspector of roads and bridges passed through a few weeks ago. Then the Inspector of Border Customs and within the fortnight both the Inspector of Police and the Inspector of Public Accounts alighted the coach at different times, audited and inspected and proceeded through to Thorgumindah on the Bullo River.
On the 9th instance, after a day or two of rest, Mr G. C. Watson, Commissioner of Crown Lands Warrego district, accompanied by a staff of officers and 5 or 6 pack horses started for Barringun, where he will be met by several surveyors of the sister colony. Their object is to mark the course of the 29th parallel of south latitude, the boundary line between the two colonies. When the work is accomplished, Thurulgoona and the other stations will no longer be matters of uncertainty and the residents of Barringum, whom the border Customs officers have hitherto regarded with some doubt as New South Welshmen will have the question put to rest.
Extract Cunnamulla News
The Zero Obelisk, Barringun marks the first official survey of the border between what were then the separate colonies of New South Wales and Queensland when an accurate definition of the border was important for legal and economic reasons. It illustrates a remarkable feat of surveying in the nineteenth century and is a reminder of the extraordinarily difficult conditions under which many early surveyors worked.