Vārāṇasi observatory



In the city of Varanasi (also called Benares, and Kashi ), right on the banks of the river Ganges, above the series of steps called Man Mandir Ghat, there is a building named Mānamandira, and on top of this building, there is an observatory. According to Bapudeva, it was built by orders of Jaya Siṃha, also known as the famous observatory builder, Sawai Jai Singh.

The coordinates of the observatory are: 25°18'28"N 83°0'39"E (google maps link)

Bapudeva gives a detailed description of many of the instruments at the observatory. He also notes that many of the instruments, especially the graduation marks, were damaged and broken at the time of his visit, making it hard or impossible to use the instruments for their original intended purposes.


 * Yāmyottara-yantra (mural quadrant)

Size: 7 1/3 cubit high, 6 cubit 1 2/3 aṅgula broad, 16 1/2 aṅgula thick.

When the sun is at meridian, the gnomon shadow strikes various quadrants giving information about the observed objects. The latitude of the obsevatory could also be found, as well as the declination, and ascensional difference of the Sun. From this the day length and the celestial longitude of the Sun could be determined.


 * unknown instrument

Consisting of four levelled planes: one large, two smaller circular (Dia. ~ 1 cubit 9.25 aṅgula, second Dia. ~2 cubit 7 aṅgula), and one square (1 cubit 11 aṅgula).


 * Samrāṭ-yantra

Consisting of a gnomon wall, inclined towards polaris. Two stony arcs, radii 6 cubits, with passages for close examination of the shadow upon them, and divided by quadrants. The quadrants are  marked near the edge, as 15 ghaṭis, each of which has 6 smaller measures within roughly 3 aṅgula each. The śaṅkupāli (edges of gnomon wall) have iron rings coinciding with the cāpapālis (edge of arcs).

It can show the hour angle (somewhat off because of 'excessive weight'). The hour angles of the planets and moon can also be determined by looking through a metal tube touching the sankupali and cāpapāli.

From this measurement, Bapudeva gives a method of finding viṣuva-kāla (right ascention) of a nakṣatras star, using daśama-lagna etc.

There is also a small samrāṭ-yantra in another part of the observatory. It's śaṅku (wall) is 6 cubits / 17 aṅgulas long, radius 2 1/3 cubits.


 * Bhitti-yantra

(no description given)


 * Nāḍī-maṇḍala (equinoctial circle)

Constructed in the plane of the celestial equator. Consists of two circles. The first: (diam 3 cubit 2 aṅgula), 4 quadrants around an iron peg pointing to polaris. It can tell the hour-angle of the northern-hemisphere-Sun/stars. The second: (diam 1 cubit 13 aṅgula), can tell the same for objects in the southern-hemisphere.


 * Cakra-yantra

It is between two walls, a rotating iron with diameter pointing at polaris. Part is covered in bronze foil. Edges are marked in degrees and 1/4 degrees. A peg at center holds a bronze paṭṭi (tube device) with a thread & index mark. It was once able find the declination of an object, but was damaged at the time of Bapudeva's visit.


 * Digaṁsa-yantra

This instrument has two circular walls (Heights: 5.5 cubits, 2.75 cubits), with degree-graduated tops. The outer wall has 4 pegs, one for each direction. There is also a 2.75 cubit high pillar in middle, and a centre-fixed gnomon.

Digaṁśa is the azimuthal angle and this instrument can be used to find it. Threads are connected to the direction pegs, and a third string to look at from the graduated walls.