Linear-Uhr, Kassel

The Linear Clock is a light kinetic sculpture constructed by Peter Hertha in 1977, located at the upper end of Kassel's Wilhelmsstraße at Ständeplatz.

Between three stainless steel columns, each offset by 120°, three identical vertical rows of incandescent lamps are arranged under a Plexiglas envelope. The interplay of the electronically controlled incandescent lamps serves to display the time. As was common with electric clocks of the time, the 50 Hz mains frequency is used as the clock generator. In addition, the clock adjusts itself by receiving the radio signal from the DCF77 time transmitter in Mainflingen.

Each vertical row of lamps is divided into three segments. The top segment displays the hours, the middle one the minutes and the bottom one the seconds. In each segment, there are two rows of lamps on top of each other, which must be read separately. To read the time, you only have to determine the number of lit lamps in the six rows and arrange the digits according to the scheme of a digital clock. Thus, at noon, only 3 bulbs light up in the uppermost segment, the first of the upper row and the first two of the lower row.

In 1981, the artist Horst H. Baumann used the principle of the linear clock for his sculpture Lichtzeitpegel at the Rhine Tower in Düsseldorf.

In 2019, the linear clock in Kassel was restored and modernized. In the course of this, it received a new location, which is only a few meters away from its old place. Here it now stands protected from delivery traffic and uses LEDs to show the viewer the time or the passing of it.