Rasivalaya Yantras

The Rasivalaya Yantras are unique to the Jaipur observatory. Each Yantra is related to one of the constellations of the zodiac, thus there are twelve of them.
  • Introduction

    Perhaps the most intriguing of all of Jai Singh’s instruments, there are twelve in all, grouped in front of the southern wall of the observatory. The design of the Rasivalaya Yantra is based on the Samrat Yantra, an equinoctial dial with gnomon aligned to the earth’s axis and quadrants parallel to the equator. This can easily be seen in the basic form of each instrument. What is also obvious is that although they share this common form, each instrument is shaped and oriented differently from the others. This feature is explained by the instruments’ function. Each Rasivalaya Yantra is related to one of the constellations of the zodiac; thus there are twelve of them. The illustrations on this page show the yantra for the constellation Cancer.

  • How it works

    The gnomon and quadrants of each instrument are aligned with the pole and plane of the ecliptic at the moment the first point in the constellation crosses the meridian. The angles of the gnomons vary from 3.5 degrees (nearly flat) to 50.5 degrees (quite steep), and their orientation varies from north by 26 degrees in each direction.

Rasivalaya Perspective Thumb

Rasivalaya Yantra for the constellation Cancer, perspective view.

Rasivalaya NS elevation thumb
Rasivalaya EW elevation thumb

Rasivalaya Yantra, for the constellation Cancer, elevations.

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