Description:
This instrument was attached to the wrist. A knob on the side is used to adjust the sensitivity of the pressure button (pelotte). This button transmit pulse waves through the metallic stem at the upper part of which is a loop. In that loop lies a counterpoised rod, on the lower end of which is attached a needle scratching the pulse waves on recording paper. A clockwork mechanism turns a roller, which winds that recording paper (smoked paper) under the needle to record a visible trace. The wrist band marked "Paris" appears to be a later addition.