This Alidade probably dates from the early 1900's and was probably a military use instrument.  It has several interesting and mysterious features.  First, note the very compact sighting scope located at one end of the instrument.  Rather than the traditional center locations with a longer scope.  Second, note the reticle.  It has 3 scales:  one is linear and labeled "grades" and the other two are not labeled and they are not linear.  Finally, the box also has an unknown function as well.  Note the 3 screws at the junction of the "L" shape.  These three screws are removable and can be screwed into a set of 3 holes on the bottom.  The function of this eludes all who have seen it.