Sign of the Time
Handcrafted sundials are elegant and can be suprisingly accurate, says Katrina Burroughs
Sunday Times, Home Section, September 9, 2007
A professional dialmaker is skilled in both the calculations and the crafts involved. Capel Tenison, of Border Sundials, in Wales, for example, produces engraved horizontal plates in brass, priced from £117.50. He marks the hours on every plate and positions each gnomon (the indicator that casts the shadow across the dial) according to the specific latitude and longitude of the client's garden, ensuring accuracy.
For, although we all use Greenwich Mean Time (and British Summer Time), the sun's position in the sky varies depending on how far west or east of the Greenwich meridian you live. Bristol, for instance, was happily operating about 10 minutes behind London until the country moved to GMT in 1880, as a consequence of the expansion of the railways.
"The maths behind it might sound complex, but some of the principles are really quite simple," Tenison says. "For instance, the angle of the gnomon always has to run parallel to the axis of the earth."