​Key to understanding the chart,

• The vertical numbers in the left hand of the chart represent above 10 magnetic north moving East. Below 10 represents magnetic north moving West. And if the line is on 10 magnetic north is fixed i.e. not moving
• The numbers at the bottom of the chart are the amount of reading taken over time
• The zig zag line on the chart is increments over 24 hours
• The line at the bottom of the chart is always fixed at 1 this is the ID of the magnetometer that has taken the readings.