Sundial for two time zones
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Being installed in Madrid or in another city a sundial can measure time in Tokyo or in any other city in the world.
Any sundial works as a precision instrument only if it is designed for specific geographical coordinates. For example, if a sundial is designed to Madrid it can not be used in Tokyo. However, any sundial can be designed so as to being installed in Madrid it can measure time in another city, for example, in Tokyo.