The Kerr Articulator was the third patented with the adjustable condylar guide feature following those of William Walker (1896; patent #'s 556,949 and 556,950 ) and Clemens Huberty (1901; patent # 686,613). It was the first one of this type with a simple and practical design and was aggressively promoted by the Kerr Dental Manufacturing Company. Interesting design features include the condylar controls placed at the level of the occlusal plane and a vertical stop table located behind the casts. Kerr's design error was not placing calibration units on the condylar controls. Alfred Gysi asserted that his claim for an incisal pin and guide was denied by the U.S. Patent Office because Kerr's posterior stop was regarded as comparable to the incisal guide.
Dr. Edgar N. Starcke's articles in the Journal of Prosthodontics have more information on the history of articulators.