Abstract: A data recording instrument having a recording sheet supply roll and a recording sheet take-up roll used for continuously recording a sensor. The instrument utilizes an axially movable rod activated by pulsing means. Movement of the rod advances the take-up roll through lever means connected to the axially movable rod. The lever means adjusts the degree of turning of the take-up roll in proportion to the amount of recording sheet accumulated on the take-up roll. The axial movement of the rod also activates marking means for charting the resultant output of at least one continuous sensor.