Sundials - World's Oldest Clocks

North American Sundial Society

nass_news_2011_april_dial_watchA novel wrist watch is being proposed which uses LED's instead of the sun to cast shadows.  Proposed by an individual named Anders who lives in Sweden, the watch, which is still just a concept, is read much like a conventional analog watch.  But instead of an hour hand and a minute hand, it uses LEDs which rotate around the outer ring of the dial and shine on a small gnomon at the center of the watch.  One LED casts a shadow for telling hours and another for telling minutes.  It is too soon to tell whether this concept watch will prove popular enough to manufacture.

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Source: http://www.tokyoflash.com/blog/2011/04/gnomon-watch-design-a-sundial-with-a-twist/