The Calculating Instruments of Jaipur

Jantar Mantar is a collection of 19 astronomical instruments in Jaipur, Rajasthan, completed in 1734.

The name translates from Sanskrit as calculating instrument. Observers used these structures to track stars with the naked eye.

Ram Singh restored the site in 1876. He inserted lead into lines and replaced plaster with stone.

The Vrihat Samrat Yantra stands 27 meters high with a face angled at 27 degrees—Jaipur’s latitude.

The monument covers a wide open area.

One ruler later turned the observatory into a gun factory. Astronomy is quieter than gunsmithing.

The Nadi Valaya Yantra has two sundials on different faces. The two faces represent the north and south hemispheres.

The sun penumbra can be 30 millimeters wide, making the one millimeter scale marks decorative.