The white arc at the left determines the time, which is Jaipur local time. Before standard time, each town had its own time, which was completely accurate, though out of step with other places.  Indian Standard Time, by the way, varies from Greenwich Mean Time by 4 1/2 hours. Nepali time differs from Indian Standard time by 15 minutes.

The small instrument on the right is called Dhruva Darshak Yantra, and is used to measure the position of the pole star.

A multi-function instrument, with fine engravings of longitudes, latitudes and planets. It's used to track planetary position and rotation speeds can determine the dates of eclipses. 

This instrument follows the passage of the sun between the northern and southern hemispheres. From March 21 to September 23 the sun is in the Northern hemisphere, and from September to March it's in the southern hemisphere. When one side of the instrument is in the sun, the other, identical side is in the shadow.

This is a set of 12 instruments, invented by Jai Singh, which correspond to the signs of the zodiac.

One of the twelve zodiac instruments.

Invented by Jai Singh, this is a multi-purpose  instrument. It tells the time, measures the coordinates of celestial bodies, and among other things, the zodiac symbol of the day.

It's possible to climb inside between the slabs.

This instrument measures celestial latitude and longitude.

Used for finding out the azimuth and attitude of the sun, moon or stars.

To find out the Meridian Pass Time and the declination of a particular planet. The wheels are on hinges, and the holes in the middle of the circles can fit other instruments.