This model of Hall's Automatic Anatomic Articulator was produced in 1924. Hall changed the name to Hall's "Arbitrary" articulator. Hall contended that this instrument embodied a feature that corrected his fundamental mistake by adopting a horizontal protrusive movement. This articulator included an adjustable incisal inclination feature and a mechanism for moving the upper arm in a straight protrusive motion. The lateral wings of the incisal guide remained at 45 degrees. The mounting jig places the occlusal plane at the level of the hinge axis.
Dr. Edgar N. Starcke's articles in the Journal of Prosthodontics have more information on the history of articulators.