1. Vrihat Smarat Yantra: The Huge Sundial
Vrihat Smarat Yantra is a huge sundial placed at the center of the Jantar Mantar observatory. It is 27 m long and renowned as the tallest sundial in the World. The Samrat Yantra, translating to ‘supreme instrument,’ is an equinoctial sundial and measures time up to the precision of two seconds.
2. Laghu Smarat Yantra
Popular as small Smarat Yantra, it is a bit smaller in size and its time calculation accuracy is up to twenty seconds. The ramp of sundial points in the direction of the North Pole; hence Jaipur time is easily calculated where the position of the ramp’s shadow falls on the fine divisions of the carved scale. The shadow on the triangular wall of the yantra tells the local time.
3. Ram Yantra
Ram Yantra measures elevation and azimuth of the Sun and planets. The instrument consists of a pair of tube-shaped structures opening to the sky. All structures have a pole of equal height at the center. It is inscribed with scales indicating angles of altitude and azimuth of extra-terrestrial bodies.
4. Jaya Prakash Yantra
This yantra is made up of two hemispherical bowls like sundials of graded marble slabs. The inverted image of the sky falls on these slabs, and the displacement of inverted shadows helps to detect the hour angles, elevation, azimuth, and accurate position of heavenly bodies.
5. Chakra Yantra
The chakra yantra, Jantar Mantar, has a ring-like instrument that helps in calculating the hour angle and coordinates of the Sun. It comprises four semi-circular arcs, on which the shadow falls from gnomon, hence detecting the declination of the Sun all four times in a day.
Another important instrument of Jantar Mantar is Digamsa. It is a pillar in the middle of two concentric outer circles, which helps predict the sunrise and sunset timings in a day.
With two circular plates facing south and north, Nadivalaya represents the two hemispheres of Earth. The wall of the plates is inclined at such a gradient that the instrument is always parallel to Earth’s equatorial plane.
8. Karnti Vritya
Jantar Mantar’s visit to Jaipur is not complete if you don’t get to see Karnti Vritya. It is an instrument used especially to measure the solar sign of the Sun in the daytime.