Jantar Mantar is the name given to observatories built by Maharaja
Sawai Jai Singh II of Jaipur. While it exists in four cities in all,
the sundials at Jaipur are considered to be the most exquisite and
Jantar comes from Yantra or instrument, and Mantar comes from Mantra
or chanting, which makes the Jantar Mantar a "chanting instrument".
instance, one of the instruments is an equinoctial dial, consisting a
gigantic triangular gnomon with the hypotenuse parallel to the Earth's
axis. On either side of the gnomon is a quadrant of a circle, parallel
to the plane of the equator. The instrument is intended to measure the
time of day, correct to half a second, and declination of the Sun and
the other heavenly bodies.
Maharaja Jai Singh II of Jaipur constructed two of these massive
The Yantra Mandir (literally the 'temple of instruments', and often
called the Jantar Mantar) is in the modern city of New Delhi, Delhi.
It consists of a collection of architectural astronomy instruments,
built by Maharaja Jai Singh II of Jaipur, for his own use, from 1724
onwards. The primary purpose of the observatory was to compile
astronomical tables, and to predict the times and movements of the
sun, moon and planets. Some of these purposes nowadays would be
classified as astrology.
Jai Singh later had another similar observatory, now known by the same
name, built for him at Jaipur.
Jantar Mantar is an important landmark of Delhi and a unique edifice.
It is an observatory built by Sawai Jai Singh II, the erstwhile ruler
of the princely state of Amber and a contemporary of the Mughal
emperor Aurangzeb. The various abstract structures within the Jantar
Mantar are, in fact, instruments that were used for keeping track of
celestial bodies. Nevertheless, the Jantar Mantar is not only a
timekeeper of celestial bodies: it also tells a lot about the
technological achievements under the Rajput kings and their endeavor
to unravel the mysteries pertaining to astronomy.
Monument of India
This unique observatory was completed in 1724 and remained operational
only for seven years. Astronomical observations were regularly made
here and these observations were used for drawing up a new set of
tables, later compiled as Zij Muhammad Shahi dedicated to the reigning
monarch. Jai Singh named his observatory Jantar Mantar (actually
Yantra Mantra, yantra for instrument and mantra for formula). It is
dominated by a huge sundial known as Samrat Yantra, meant to measure
the time of the day accurate to within half a second and the
declination of the sun and other heavenly bodies. Jai Singh himself
designed this yantra. Other yantras were also meant for the study of
heavenly bodies, plotting their course and predicting eclipses. The
two pillars on the southwest of Mishra Yantra are meant to determine
the shortest and longest days of the year. Interestingly, in December
one pillar completely covers the other with its shadow while in June
it does not cast any such shadow at all.