The apparatus is signed by the physicist Karl Rudolph Koenig (1832-1901), a student of the great Hermann von Helmoltz (1821-1894) at the University of Könisberg.
It consists of eight steel tuning forks contained in a wooden box (height 11.6 cm, depth 34.5 cm, width 58 cm), three wooden supports and a sturdy U-shaped horizontal wooden base. Each of the tuning forks is mounted on a hardwood support of square section and have two brass disks at the extremities of their prongs, one of which supporting a small mirror and the other counterbalancing the former to ensure that the tuning fork vibrates regularly for a long time.
Of the original eight tuning forks, one is missing, three have a fixed frequency and in the other four the prongs are equipped with cursors which can be set in different positions, each of which corresponding to a different, precisely determined frequency. ...continues