The six unusual structures provide excellent opportunity for the study of astronomy as in those days.
The largest of the instruments, known as the Samrat Yantra (the supreme instrument), is a huge sundial. The other five instruments indicate
the movements of the sun, the moon and other celestial bodies. New Delhi Municipal Corporation has recently built the tallest building of Delhi housing the
Corporation's offices, adjacent to Jantar Mantar.
Jantar Mantar of New Delhi is in fact an extraordinary solar observatory lying on the Parliament Street leading to Connaught Place. Situated amidst modern buildings, the medieval era structure of Jantar Mantar of New Delhi draws attention of all and sundry.
Jantar Mantar is a prime attraction of Delhi. It holds a prominent place in Delhi tourism. The medieval observatory, built of plastered brick, is painted in uniform salmon-pink colour. It's present unspoilt presence lends credit to the British. It was restored by the British in 1910 AD.
The solar observatory was commissioned by Maharaja Sawai Jai Singh II of Jaipur and came into existence in 1725 AD. The Maharaja commissioned five observatories of this type in five major cities of India- New Delhi, Jaipur, Udaipur, Varanasi and Ujjain. The Jantar Mantar built in New Delhi was the first among them. These solar observatories helped to quench the quest regarding cosmos and at the same time helped provide accurate time and movement of various stars and planets to execute auspicious ceremonies.
The strange shapes are, in fact, giant versions of contemporary astronomical instruments. In the centre, the Samrat Yantra, in the form of a great triangular gnomen, measures time to an accuracy of 0.5 seconds. The huge sundial's name, meaning Prince of Dials, was chosen by the Maharaja. To the south, the varying positions of the stars are indicated on two indented circles.
Jantar Mantar is a masterpiece of architecture. Historically, the observatory or Jantar Mantar in
Delhi was the first one built by Jai Singh. It is here that the principal observations were made, which were to
form, the basis of his new tables, the Zij-e-Muhammad-Shahi (Muhammad Shah's astronomical tables). The Jantar
Mantar in Delhi was built in 1724 AD. Jai Prakas, Ram Yantra, Samrat Yantra, a mural quadrant made of stone and
lime and some metal instruments with perfect stability were instruments of Jai Singh’s own invention. Misra
Yantra was probably added during the reign of Madhu Singh.
The observatory, Jantar Mantar in Delhi, is about 3 kms south from the Jama Masjid in Chandani Chowk
area. The observatory borders (on the east) the road leading from the railway station to the Secretariat and Government
House. It consequently is a notable feature in the New Delhi, apart from its historical value. The general plan of
the observatory shows the following structures—
The Samrat Yantra, the supreme instrument, is a huge equinoctial dial. The Samrat Yantra is the central building
of the observatory. It is tall and most imposing, although a considerable portion of it is below the surface of the
earth. It is, indeed, built into a quadrangular excavation some 15 feet deep, 135 feet from east to west, and 120
feet from north to south. It is about 60 feet above the earth's surface.
The Jai Prakas consists of two hemispherical structures, just to the south of the Samrat Yantra. These intruments
are concave and complementary hemispheres. Jai Prakas is reflection of Jai Singh’s ingenuity. Theoretically, only
a single hemisphere is necessary, but, to facilitate observation, pathways are cut into the surface; and the second
Jai Prakas is so constructed that the two instruments together show the complete surface. The diameter of the Jai
Prakash is 27 feet 5 inches.
The Jai Prakas consists of two hemispherical structures, just to the south of the Samrat Yantra. These intruments are concave and complementary hemispheres. Jai Prakas is
reflection of Jai Singh’s ingenuity. Theoretically, only a single hemisphere is necessary, but, to facilitate observation, pathways are cut into the surface; and the second
Jai Prakas is so constructed that the two instruments together show the complete surface. The diameter of the Jai Prakash is 27 feet 5 inches.
The Ram Yantra consists of two circular buildings to the south of the Jai Prakas. These circular buildings are complementary
to each other. A circular wall encompassing a pillar at the centre is part of circular building. The height of the walls,
from the graduated floor, is equal to the inside radius of the building measured from the circumference of the pillar to
the wall.
The Misra Yantra or mixed instrument is located some 140 feet away in north –south from the Samrat Yantra.
This instrument was named thus because it combined in one building four separate instruments. Of these the Niyati
Yantra occupies the middle of the building, and consists of a gnomon with two graduated semicircles on either side.
On either side of the Niyati Yantra, and joined to it, is half of an equinoctial dial, constructed on the same principle
as the large Samrat Yantra. On the west side of the building is a second quadrant, the face of which is horizontal
instead of being parallel to the axis. It is called the Agra Yantra or ‘amplitude instrument. Its use does not seem
to have been understood by the restorers. There are two pillars south-west of the Misra yantra. A measuring platform,
just south of the Misra Yantra is also a speciality. On the east wall of the building is a graduated semicircle called
Dakshinovritti Yantra, used for obtaining meridian altitudes.