When i got this Zither, the company logo in the sound hole was completly destroyed.
But i´m sure, because of some fragments that this Zither was built by Friedrich Idinger in Stuttgart.

Idinger played Zither in stuttgarter tuning by himself. He also invent some tunings.
This Zither have six fretboardstrings. In the year 1882 he got a patent on a fretboard with seven strings(e´´e´´a´d´g c F).

Probably my instrument is built arround 1880.

The stuttgarter tuning hasn´t any homogeneous system. Not on the fretboard and not on the accompaniment strings.
Mostly they had munich tuning in accompaniment strings.

Some examples for fretboardtunings:

six strings:

e´´a´a´d´g c

e´´e´´a´d´g c

h´e´´a´d´g c....

seven strings:

e´´e´´a´a´d´g c

h´e´´e´´a´d´g c

In addition this Zither is a so called "Halbelegie", the diapason of fretboardstrings is 445mm.