Abstract: A recording system with a chart recorder having a movable pen arranged for providing a record on a moving chart of the varying value of a variable has the feature that means are arranged for causing the pen repetitively, at intervals or at selected moments or occasions to execute a traverse on the chart and in so doing to record the current value of a second variable on the chart in binary representation by marking or not marking chart zones crossed in the traverse and allotted to respective information bits for the second variable value. A particular application of the system provides repetitive recordings on the chart of clock and calendar times. Each recording of the second variable is clearly distinguishable from the record trace of the first variable and scarcely interrupts the continuity of the latter.