The self-reducing tacheometer was made at the end of the 19th century. The instrument is something quite special to look at and one of the most valuable items in the collection of the University of Ljubljana, Faculty of Civil and Geodetic Engineering. Numerous toric levels, a compass, microscopes for vernier reading, a conspicuous telescope, and numerous clamping and micrometer screws give the appearance of complexity to the instrument.

The instrument does not have a vertical circle, as it operates on a different principle than the classical three-hair tacheometers. It is one of the first, if not the first, self-reducing tacheometers in the world. The Hammer-Fennel technology of self-reducing measurement of distances and height differences was first described for just such an instrument on 29 March 1902 in the Sweizerische Bauzeitung, a Swiss construction profession journal. Instead of crosshairs, half of the field of view is occupied by a diagram with a base and a distance hair and elevation hairs. The distance of the elevation hairs and distance hairs from the base hair varies as the elevation angle of the observation (the tilt of the line-of-sight axis) changes. The change is coordinated so that horizontal distances and height differences can be calculated directly/instantly from the tacheometric staff readings. The distance hair constant is 100, and the elevation hairs constant is 20. Measurements can only be taken in one circular position of the telescope.

The instrument was completely restored in 2016.