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The bottom part of Page-1 allows you to calculate magnetic declination for a specific time or place. The process is relatively simple. As you make changes to the location, elevation and date, the program automatically recalculates the declination and displays the result.
Elevation and Date. To accurately predict the declination, the program must have the elevation of the cave and the date the survey was carried out. Depending on how the Geographic Calculator was run, Compass may have taken the information from the survey files. Otherwise, you must enter this information manually.
Entering Dates. Dates are displayed in simple numerical format. There are two ways to change the date:
1. Click on the “down arrow” to the right of the “date box.” This will display a small calendar. You can select any day on calendar by clicking on it. To change the month, click on the arrow buttons in the upper right and left corners of the calendar. To change the year, click once on the year-display. An up and down arrow will appear to the right of the year. Clicking on these buttons, causes the year to increase or decrease.
2. Click on any field in the date box. This will highlight that field. Now hitting the Up and Down arrows on your keyboard will cause the field to increment and decrement.
Entering Elevation. This value is the elevation of the cave above sea level. Elevations can be in either feet or meters and you enter them by typing the numbers into the corresponding box. As you change one value, the other value is automatically recalculated so you always see the correct value in both the feet and meters.
Important Note. It is important that location be set properly for the declination to be accurate. Depending on how the Geographic Calculator was run, Compass may have taken the information from the survey files. Otherwise, you must switch to the first page and enter this information manually.