'SITZMASCHINE' A STAINED BEECH AND BENTWOOD ADJUSTABLE ARMCHAIR, DESIGNED CIRCA 1908

cf. D. Ostergard, Bent Wood and Metal Furniture: 1850-1946, New York, 1987, p. 258 for an illustration of this chair model.
C. and P. Feill, 1000 Chairs, Cologne, 1997, p. 129 for another illustration of this model.