This page should enable you to create a printable, functional wall sundial, which you can test, to ensure that the your finally Wall sundial from OlneyStone will be accurate.

The code below, will generate a sundial to work with the local time, (defined as the sun's position overhead). Depending on your longitude, this will vary alittle from Greenwich Mean Time, when the sun is overhead in London, and from which the UK time is defined. For example, Plymouth is around 15 minutes behind GMT, being further west, so when the sun is at its highest at London, it is not quite at its highest at Plymouth. The java code below, currently does not have this adjustment in it (this is planned), but OlneyStone can ensure this additional accuracey (if required).

There are basically 3 inputs that are required for a Wall sundial.
  1. The latitude of the location of the sundial. This can either be obtained from an Ordinace Survey Map, or by typing in your postcode on the following  BBC weather website http://www.bbc.co.uk/weather/
  2. You next need to obtain the direction that the wall is facing. To do this use a magnetic compass to determine this.
  3. As magnetic north is not the same as true north (where the north pole is), an adjustment is required. This adjustment cane be obtained from the top of an ordinate survey map, or by entering your latitude/longitude into the online calculator on the following US government geopysics webpage http://www.ngdc.noaa.gov/seg/geomag/jsp/struts/calcDeclination

With these three pieces of information, the java application (ensure that java is enabled in your browsers preferences) can be filled out below.

The red line on the displayed sundial is the line on which the gnomon (pointer) is placed: for non south facing sundials is this not vertical (although the 12 noon position will always be vertical). The gnomon will be a pointer whose angle from the wall is defined per the angle indicated, with the "point" of the gnomon at the center of the sundial.
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