JAIPUR JANTAR MANTAR :WORLDS LARGEST SUNDIAL

4 min readFeb 10, 2017

“Jantar Mantar” these two magical and mysteries words chanting in India by many people in their childhood to fulfill their magical dreams but these words are more than that. The term “Jantar Mantar” literally means “instruments for measuring the harmony of the heavens”. The astronomical observatory established by the king Sawai Jai Singh have International importance. The Jantar Mantar houses various architectural and astrological instruments that have caught the interests of astronomers, historians and architects around the world. It is considered to be one of the largest observatories ever built.

In the early 18th century Maharaja Sawai Jai Singh II of Jaipur constructed five Jantar Mantar in total in New Delhi, Jaipur, Ujjain, Mathura and Varanasi. They were completed between 1724 -1735. The Jantar Mantar observatory was constructed between 1728 -1734. It is the largest observatories among five and best preserved and still running. It is a collection of 19 architectural astronomical instruments. It features the world’s biggest stone sundial “Smarat Yantra”.

largest sundial (Vrihat Smarat Yantra)

The Vrihat Samrat yantra is a sundial that can give the local time to an accuracy of 2 seconds. Restored A.D. 1901 tested by jotshi Gokul chand bhawan for finding time and declination and hour angle of the heavenly bodies. It is the largest sundial ever built with a gnomon arm 22.6 meter high and largest quadrants of radius 15.5 meter. The shadow of the triangular wall, which is placed in the north-south direction with an angle equal to the latitude of this location moves equal distances in equal time intervals, on the eastern and western side quadrants. This movement is calibrated to read the local time. The western and eastern quadrants are divided into 6 hours each, for the morning and the afternoon segments respectively. Each hour is divided in 15 minutes and later in 1 minute parts. The minute part has ten subdivisions each of 6 seconds each of which again has three small divisions of 2 seconds each. The correction factor which is to be added for the day is displayed to convert the time obtained from this instrument to the clock time.

Small samrat yantra

The small samrat yantra is a sundial that can give the time to an accuracy of 20 seconds. The shadow of the triangular wall of the yantra, falling on the eastern & western side quadrants, tells the local time. The triangular wall, with the angle inside the wall is place exactly in the north-south direction. The shadow of the triangular wall moves equal distances in equal time intervals on the quadrants. This movement is calibrated to read the local time. The western & eastern quadrants are divided into subdivisions, each of 6 hours, for the morning and the afternoon segments respectively. Each hour is further divided into 5 minutes and 1 minute divisions, and each 1 minute division is subdivided into 3 divisions each of 20 seconds. The correction factor, to be added to convert the sundial time to the clock time for the day is displayed near the instrument.

Rasivalaya (zodiacal circle)

Rasivalaya are instruments for measuring the celestial latitude and longitude of the celestial bodies. There are twelve instruments which represent the twelve signs of the zodiac, one for each measurement to be done when the corresponding sign of the zodiac transits the meridian.

Jaya prakash yantra

Nadivalaya (equatorial instrument / circular dial)

The nadivalaya has two circular plates, facing north and south which are its dials. The wall of the plates is inclined towards the south at such an angle that the instrument remains parallel to the plane of the Earths equator.

Chakra yantra

The chakra yantra is a ring instrument which measures the global co-ordinates of declination and the hour angle of a celestial object.

Ram Yantra

The Ram Yantra can measure the local co-ordinates of altitude and azimuth of a celestial object.

Krantivrtta

The krantivrtta is an instrument that is meant to measure the celestial latitude and celestial longitude of an object in the sky. It is also used for measuring solar sign of the sun in daytime.