The mysterious Lake George towers with a surprising legacy

The Canberra Times

It looked like a bushranger-era safe house, but this lakeside ‘fort’ near Canberra marked something far more significant: the birthplace of NSW’s survey network.

Transcript

00:00On the shores of Lake George near Canberra is this mini castle, but its purpose has nothing

00:09to do with defence. It was built in the 1870s to mark the north terminal of a baseline used

00:17for trigonometrical survey in the colony of New South Wales. The baseline extends about

00:229km along predominantly flat land on the eastern side of the lake. The baseline was the reference

00:30point from which many surveys in New South Wales originated for over a century. Fundamental

00:38for the design and construction of large-scale civil infrastructure such as roads and railways,

00:45this baseline was pivotal in the development of 19th century Australia.

00:51The land at the south terminal is a couple of metres higher than at the north terminal,

00:57so the survey marker at the south end is mounted atop a smaller can of rocks rather than on top

01:05of a tower. The precise location of both the north and south terminals is marked by a tiny

01:14platinum dot which is hidden under a stone cap. Incredibly, despite the significant advancements

01:22in technology, when in 2006 the 1874 baseline was tested, it was shown to be accurate within

01:33just 21 millimetres. Another historic treasure on the shores of Lake George.

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