Find "True North" using the shadow method

For this you need:

• a large piece of paper or carton
• a straight rod - a pencil will do very well
• "Prestik" or some other means of securing the rod.

• Find a sunny, flat and level (horizontal) place in the area where you intend to place your sundial.
• Firmly secure the paper to the flat area.
• Place the rod in the middle of the northern side of the paper. Make sure it is perpendicular to the paper. We shall call this point N. If you prefer, you can make your marks directly on the surface.
• Mark the position of the shadow every 10-20 minutes from about 10:00 till 14:00. The more often you take measurements the easier it will be to draw a smooth curve later.
• Draw a smooth curve through the marks you have made.
• Find the shortest distance between the curve and the base of your rod. Mark this point, S, on the curve.
• The line from this point, S, to the base of your rod, N, is your true north-south line.
  An example of a shadow plot is shown below.