Sundial

This is an unusual sundial made of Valentia Slate.  It used to be situated beyond the Fog Signal House.  It was repositioned here and set by Capt. Eoin Deignan of CIL, who also set the sundial for the Air India Disaster Memorial, designed by Ken Thompson, on Sheep’s Head.  The time shown is ‘Local Apparent Time’ or Sun Time which can be converted to Clock Time by making allowances for three factors:

1. Sometimes the sun is ‘slow’ or ‘fast’ and there is a table for the ‘Equation of Time’ for those days, which have to be added or subtracted.
2. The difference in longitude between Mizen Head and Greenwich is 39½ minutes so this is always added to the dial time.
3. One hour has to be added on for ‘Summer Time’.

The gnomon or ‘hand’ has to be read on the western age of the shadow before noon and the eastern edge after noon.