The heating pad was invented by Zeppo Marx, the youngest of the famous Marx Brothers comedy team. His heating pad was intended to revolutionize the way in which medical patients were kept warm. Until Marx's invention, patient body temperature was maintained through the use of towels, which were soaked in hot water and wrung out before they were applied to the body.
Marx considered the use of towels to be inefficient because of the need to regularly replace them as they cooled. His alternative consisted of a steam generator, a vapor delivery pad and a connection between the two. Medical staff could manipulate the apparatus so that the hot steam was directed to specific regions of their patients' bodies.
The heating pad was one of two medical inventions contributed by Marx. He also invented the cardiac pulse rate monitor to be worn around the wrist like a watch. The invention was intended for use by people with heart problems, allowing them to monitor their own pulse rate, amplitude and regularity. The system was essentially an electrical circuit with a battery and a switch. With each beat of the heart, the switch closed to complete the circuit and rotate a magnet. In turn, the magnet manipulated the visible dial.