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The Nadivalaya has two circular plates, facing North and South which are its dials. The wall of the plates is inclined towards the South at such an angle that the instrument remains parallel to the plane of the Earth’s equator. The rods (gnomon) emerging perpendicularly from the plates are parallel to the axis of rotation of the Earth. The shadows of the rods move along the scales on the dial plates, indicating the local time.

Each dial plate is divided into three circular scales, two of which have markings for the hour and minutes. The third scale is marked for the determination of the zenith distance. To the time indicated by the circular scale, a correction factor as displayed for the day at the Observatory needs to be added to obtain the clock time.

The dial plate facing south is sunlit from the autumn eqnhox to the spring equinox and is to be used for telling the time. The dial plate facing North is sunlit from the spring equinox to the autumn equinox.