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Ringdials, Timepieces and Scientific Instruments
Ringdials
Large Ringdial - £80.00
Universal Equinoctial Ringdial - £26.00
Augsberg Equinoctial Ringdial - £85.00
What are Ringdials and how are they used?
Ringdials are probably the earliest type of time measurement and date from thousands of years before mechanical devices. Devices range from a simple shepherd's dial to the complex and sophisticated multi functional Nuremberg dials of the 16th and 17th centuries. The earliest sundials, like Cleopatra's Needle, were upright obelisks, but in order to measure true solar time, the angle of a sundial's spike, or gnomon, must correspond with the angle of latitude.
To find the altitude of the Sun, the shadow of the pin was made to fall on the angle or 'nautical' scale on one side of the instrument. To find the time, the suspension ring was set at the latitude, the small index with the pinhole was moved to coincide with the date on the central bridge, and the point of light from the pinhole gave the time on the hour ring.
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