This apparatus appears in the following catalogue:
Andersen Hemming, Historic scientific instruments in Denmark, Matematisk-Fisiske Meddelelser 44:2, Munksgaard Copenhagen, 1995, pp.191

Link: http://books.google.gr/booksid=RUQZPb4qtkC&pg=PA433&lpg=PA433&dq=Siemens...

Inventory Number: ELE704