Originally manufactured by the Western Electro-Mechanical Company, this instrument was not produced after 1938. It had three tambours: one for the cardiosphygmograph, another for the pneumograph, and a third for either a second pneumograph or a muscular movement device. The kymograph could be geared to move the graph paper 3, 6, or 12 inches per minute. Associated Research, Inc. later produced the Keeler polygraph, similar to the original design except it permitted a galvanograph channel, and the chart speeds were 6 and 12 inches per minute. The Keeler polygraph is no longer in production.
