Hi Paul, picture of Popples Corner, border of QLD,SA & NT, Australia,
is not in the original position because the survey chain had become worn
so the links were not exactly 7.92" long or whatever they are (I cannot
remember the exact length of the links) so the boundary was not exact.
However they had agreed on a longitude, the other picture is exactly on
the boundary of the NT and QLD.
John Burey.

Yup, one link equals 7.92". 100 links in a 66' surveyors chain per my
recollection from +35 years ago. Could have been surveyors neglected
to correct for higher remperatures having lengthened chain?  Who knows?
Old school procedures now lost to GPS, etc.
Allen Koivisto