Survey spanner

[superzstuff]

Got this in a box of tools and found Gurley made survey equipment but could not find the use for this wrench. It is 4" long and has 1/4" prongs and spaces. What did it do?

[wvtools]

I looked all through my 1901 Gurley catalog.  The only wrench I could find was a small flat steel wrench used to attach a plane table to the tripod.  I imagine that your wrench may have had a similar application, maybe on a later model.