- First, place the sundial on a level surface in a spot where it is fully exposed to the sun. Push the gnomon through the holes in the top section of the sundial. Adjust so that the lower end of the gnomon touches the appropriate spot on the latitude scale. (Note: If you don't know what your latitude is, check the column marked "Lat" in the table on the back of the sundial to find out.)
- Once you've adjusted the latitude, use a compass to find north. Since the compass will point to the magnetic north pot, not the "true" north pole, consult the table on the bottom of the sundial to find the city nearest you. Check the column marked "Mag Set" to find the magnetic direction in which you should point the sundial and orient the sundial accordingly. For example, San Francisco shows a magnetic setting of 016 degrees on the compass (Note: You may round off the table reading to the nearest five-degree increment on the compass dial.)
- Read the sundial by observing where the shadow cast by the gnomon falls. Read the upper face from March to September and the lower face from September to March. The dial shows standard time. When daylight savings time is in effect, add one hour.
- To correct for the "wobble" of the earch on its axis and the varying speed of the earth in its orbit, consult the seasonal correction table on the inside of the sundial. To use the table, first fine the month and then move acros to the column representing the current week of the month. Add or subtract the minutes shown on the table from the time shown on the dial to get the correct time.
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