The wall dial to the right has been made for a situation facing due south (i.e. a wall running east - west).  Since the sun is highest in the sky and due south at noon, the twelve o'clock mark is vertical, down the middle of the back plate, and the gnomon is placed in line with this.

This is the most straight forward layout for a wall dial and the plate is marked to show the hours from 6 in the morning until 6 in the evening.  It is available in brass, 32cm x 45cm (12.5"x18") for £225   [ref DSS].

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However, very few walls run exactly east - west!  The dial to the left is what is known as a declining dial.  These are designed for use on walls facing a direction other than due east, south, or west.

As can be seen, the twelve o'clock mark is still vertical, but now the gnomon is angled to one side to make allowance for the angle of the wall.

You can also see that the hours it records are different - in this case from 9 in the morning until 6 in the evening - since the wall itself will shadow the dial from the rising or setting sun.

Needless to say, these dials have to be individually designed for their particular location - both for the angle of the wall and the latitude - but that does give the opportunity for special inscriptions to be incorporated.  Click here for an example of a recent commission comprising a matched pair of stainless steel dial designs, one for a north east facing wall and the other facing south west.

This dial is normally made of brass, 40cm x 50cm (16"x20"), but other sizes can be made on request.  [ref CWS]   Prices from £490.

Due to the slightly elliptical orbit of the Earth about the Sun, and also the wobble about its axis, the time shown on a sundial may be slow at some times of the year and fast at others.  This plate graphs the variations and enables a correction to be made to change "sundial time" to "watch time".  Incidentally, when clocks were in their infancy and were none too accurate, many had tables of the Equation of Time so that the clock could be set from a nearby sundial!  [EoT]  £35		 equationoftime.jpg (5862 bytes)

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