A rare and fully intact Gesenius and Keller oscillograph, a remarkable piece of mid-20th-century German engineering. This precision medical or scientific instrument was designed to record pulse waves via a dual-sided mechanism onto roll paper, making it an essential diagnostic tool in its era. Housed in a sturdy portable case, it features a mechanical wind-up function, analog pressure gauge, original dials, and switches—all in excellent vintage condition. The device includes the original winding key, paper roll, and internal drum mechanism, and carries a German “D.R.P. Patent” plaque, indicating a patented design. A must-have for collectors of antique medical devices, historical scientific instruments, or industrial design enthusiasts.