Troughton and Simms Theodolite for
 Kilpatrick & Co, Melbourne Serial  No 686

Kilpatrick and Co were Mathematical Instrument Makers, Opticians, Goldsmiths, Jewellers and Watchmakers operating in Melbourne at various Collins Street addresses between 1876 and 1898. This instrument was made by Troughton and Simms for Kilpatrick and Co.
The serial number # 686 matches the label on the box.

I think that the serial number must have been generated by Kilpatrick as I have never seen any serial numbers generated by Troughton and Simms.

" S R & W S C" is engraved on one of the standards. The State Rivers and water Supply Commission was established in 1905 which would date this theodolite between 1905 - 1910
Another label in the box is for Norman H Seward who were survey importers, instrument adjusters and repairers. "Seward and Davis" were shown operating at 457 Bourke Street from 1904 to  1972. I cannot find any historical details on their merger.