well just going thru some old pickies and found thin one. I remembered I took this for a Trig cache. not only that but it was an historic one as it was on the Bourke Base Line. The NSW govt decided to improve the geographical survey for better land development as farming was getting more involved and important. Therefore from 1890 to 1916 the trigonometrical survey was extended. their was two base lines one around Lake George near Canberra. A baseline needs aprox 20 miles along a flat straight surface and all sorts of triggy measurments can be worked out by the boffins. The Bourke Base line was started in 1911 and by 1916 the Lake George triangulation had reached the Bourke Base line.At this time it was partially suspended due to the war.
Work was continued in 1927. on March 26th 1931 the final details were forwarded to the Surveyor General.
Thanks Acko