The Noon Sundial at the London Stock Exchange
by Steve Taylor
Title
The Noon Sundial at the London Stock Exchange
Artist
Steve Taylor
Medium
Photograph
Description
This noon mark can be found at Paternoster Square, EC4, London
Noon marks
The simplest form of sundials do not give the hours, but rather the moment of 12 midday. In the past, such dials were used to allow people to set mechanical clocks, which were often very inaccurate to the correct time.
In US colonial-era houses, a noon-mark can often be found carved into a floor or windowsill. Such marks indicate local noon, and they provide a simple and accurate time reference for households that do not possess accurate clocks. In modern times, some Asian countries, post offices have set their clocks from a precision noon-mark. These in turn provided the times for the rest of the society. The typical noon-mark sundial was a lens set above an analemmatic plate. The plate has an engraved figure-eight shape, which corresponds to plotting the equation of time versus the solar declination. When the edge of the sun's image touches the part of the shape for the current month, this indicates that it is 1200 noon.
Uploaded
June 21st, 2012
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