This dial stone is a test piece for the new obelisk sundial, and is on a board at the correct angle for one of the faces of the obelisk. It faces East and inclines 61° to horizontal so the shadow of the temporary plastic gnomon will show the time.
Obelisk sundials carved in stone were popular in Scotland in the 17th and 18th centuries. Quite recently stonemasons in Fife have done the work to carve a new obelisk sundial for one of their clients. Its dials have remained blank for mathematical calibration. Macmillan Hunter are responsible for the calibration and have supplied detailed dial instructions and drawings for the mason to use together with the required set of geometric bronze gnomons.
The oldest and most important obelisk stands at Drummond Castle and dates from 1630. It has a vertical shaft that supports a multi-facet capital and taper finial, and has 61 individual dials. The stonemason and a mathematician would have worked closely together to complete such a complex design.
The new obelisk is modelled on Drummond Castle’s though simplified and on a reduced scale. It has dials on all four North South East and West sides. The capital stone has upper and lower sloping dials, while the ones on the taper finial reduce in size towards the top. Below the capital stone, dials on the shaft are concave. The test piece in the photo was part of the preparation for incising the mathematical hour lines and numerals into stone.