The Jantar Mantar in
Jaipur was built in 1734 and was one of the most precise astronomical
instruments of its time. This UNESCO World Heritage Site is so accurate and
enduring that it is still used today for astronomical observations and
calculations.
Jantar Mantar means
"instruments for measuring the harmony of the heavens" and is the
name given to the king of Jaipur, Raja Jai Singh's observatory. It is located
in the city of Jaipur in the state of Rajasthan. It’s construction began in
1728 and was completed in 1734. The young king built four other observatories
in Delhi, Ujjain, Varanasi and Mathura. The one in Mathura has almost
disappeared today. The Jaipur Jantar Mantar is the largest and best preserved
of the five. At Jaipur, he wanted to build an observatory that would dwarf all
the others of his time, and he chose stone as the material for instruments of
unparalleled grandeur. He From a practical point of view, stone lasts longer
than brass and wears better. Where clearly visible surfaces were needed for
complete accuracy, he used marble.
The observatory is still
in use today, both for teaching and calculation purposes, and retains
extraordinary accuracy. These futuristic instruments have a surreal, abstract
beauty. Walking into the observatory is like stepping into some lunar
landscape; the visitor is surrounded by elegant yet alien structures whose
purpose remains a mystery. But there is nothing abstract about the workings of
these massive geometric instruments. Each serves a particular function in
charting and mapping the movements of the brilliant endless sky that stretches
above.
Small Samrat Yantra
This is a sundial. It
consists of a right-angled triangle, the hypotenuse of which is parallel to the
earth's axis and which casts a shadow on one of the two quadrants below it.
Each edge of the quadrants is marked in hours, minutes, and degrees. It gives
the time to an accuracy of twenty seconds. To read the time, stand facing the
steps that form the hypotenuse. The arc on your left will show the time from
sunset to midday; the one on your right tells the afternoon time. To get an
accurate reading, read the dial at the point where the shadow is sharpest.
All the sundials here are
constructed at the latitude of 27 degrees north – Jaipur's latitude – and the
time is local Jaipur (that is, solar) time. To correct this with the Indian
Standard Time, anything from 1 to 32 minutes must be added, according to the
time of year and the sun's position. There is always a board by the instrument
showing how much must be added.
Large Samrat Yantra
An enormous sundial that
towers majestically over the observatory. It operates on the same principles as
its smaller counterpart, but it is ten times bigger and thus accurate to two,
rather than twenty, seconds. The scale is measured in divisions of one minute,
six seconds, and two seconds. The complete stability of the instrument is
assured by the arches cut in the gnomon wall, which allow the wind to pass
through them. The gnomon is ninety feet high and is used for finding the time
and declination. Its edges are graduated, as are the arcs, and the observer
climbs the steps to read them.
Every year on guru
purnima, an especially holy full-moon day in the Hindu month of Ashada
(Jun-July), on which the guru is worshipped, Jaipur astrologers climb the
central stairs and fly a white flag from the top of the gnomon. On the basis of
the direction the flag takes the texts are consulted, and the length,
heaviness, and outcome of the monsoon are predicted for the surrounding area.
Like weathermen the world over, the astrologers claim great accuracy!
On either side of the
samrat yantra are a remarkable pair of sextants. These are high, narrow
chambers set within the walls of the yantra. Each chamber has two small square
openings high up in the south wall, the only place that light can enter. Each
day, at noon, the sun shines through these apertures for about a minute, and
the light falls on a graduated arc, made of plaster. From reading the position
of the dot of light, the altitude, declination, zenith, and distance of the sun
can be seen. The variation in the sun's diameter can also be accurately measured,
and even sun spots could easily be observed.
Dhruva Yantra
A brass instrument for
finding the position of the Pole Star at night, it also serves to show the
position of the twelve zodiac signs, each comprising 30 degrees of the
celestial circle, and measures the declination of the sun (that is, how many
degrees north or south of the equator it is). The instrument is graduated and
inscribed in Hindi characters, showing both time and position. While nowadays
Indians reckon angles in degrees and minutes, the traditional method of
calculating time is based on a different system. The basic unit of this system
is the human breath, reckoned to be equivalent to a length of 6 seconds.
4 breaths = 1 pala (24
sec.)
60 palas = 1 gati (24 min.)
60 gatis = 1 day (24 hrs.)
60 palas = 1 gati (24 min.)
60 gatis = 1 day (24 hrs.)
Narivalya Yantra
A sundial with two
masonry dials, one facing south and the other north. The former is used when
the sun is in the Southern Hemisphere, from September 21 to March 21, and the
latter when the sun is in the Northern Hemisphere, from March 21 to September
21. The central iron pinpoints to the pole. At noon the sun falls on the
north-south line; before noon the shadow will lie to the west, and after noon
to the east. The time is read in the normal way.
The
large Samrat Yantra in the background with the Narivalya Yantra in the left
foreground.
Observer’s Seat
Jai Singh's private
little building from which he supervised the observations that were carried
out.
Large and Small Kranti Yantra
An astrolabe made of masonry
and brass. One of the circles rotates in the plane of the equator, the other in
the plane of ecliptic (the circle of the sun's path). It is used for the direct
measurement of the longitude and latitude of the celestial bodies, and it can
be used day or night.
Raj Yantra
"The king of
instruments," this astrolabe is a map of the visible portions of the
celestial sphere, which can be used to calculate a vast amount of astronomical
data. A telescope is fixed to a rod that passes through the central hole. The
back of the yantra is fitted with a bar used for sighting. The plain disk to
the left is intended for use as a blackboard, to record observations and
calculations as they are made.
The yantra is still used
once a year (in August) to calculate the Indian calendar. All the details and
festivals of this calendar are based on the Jaipur Standard, as they have been
for the last 250 years. There are twelve divisions or months in the traditional
Indian calendar, spread over the six seasons of spring (March-May), hot season
(May-July), monsoon (July-September), autumn (September-November), winter
(November-January), and cold season (January-March). In practice, though, the
Western calendar is in use throughout India, but there are also two indigenous
calendar systems which are sometimes referred to in inscriptions and datings.
In the north there is the
Vikrama era, which dates from 57 B.C., and in the south there is the Shaka era,
which began in A. D. 78.
Unnathamsa Yantra
A huge graduated brass
circle used for finding the altitudes of celestial bodies. Notice the brass
pointer attached to the center of the circle and fitted with sights for
observation. The circle can be revolved so that observations can be made at any
time, day or night, and the sunken steps allow any part of the circle to be
read.
Disha Yantra
Points to the north.
Dakshina Yantra
A wall built aligned
along the north-south meridian. The inscribed arcs on either face of the wall
are made of marble and marked in degrees and minutes. It was used for observing
the position and movement of heavenly bodies when passing over the meridian (an
imaginary circle linking the poles that the sun crosses at midday).
Rashivalayas Yantra
Twelve sundials, one for
each sign of the zodiac. You can easily find your own sign. Each instrument
works in exactly the same way as the samrat yantras. The instruments have been
so constructed that one is available at the instant each zodiacal sign crosses
the meridian; hence they enable observations to be made approximately every two
hours.
Each constellation has
its own position, and this can be read off the appropriate instrument.
Astrology and astronomy were two parts of the one science, as far as Indians
were concerned; astronomy was the pure science, and astrology the applied.
Because all human and earthly activity was considered to be inescapably bound
up with the movement of the heavens, astrology had tremendous importance in
determining which days were auspicious, who had what sort of character, what
the future held, and so on.
Jai
Singh's Varanasi Jantar Mantar in 1777.
Small Ram Yantra
This is essentially a
working model of the large ram yantra, for measuring the altitude and azimuth
of the sun. In case of damage, all the large instruments have exact scale
models for reference.
Jai Prakash Yantra
This elegant instrument
is the piece de resistance of the Jaipur Observatory. It acts as a double check
on all the other instruments and is unique to the Jantar Mantar. The Jai
Prakash measures the "rotation" of the sun. It consists of two
hemispherical cavities set in the ground. They are complementary; if put
together they would form one complete hemisphere, which would be a map of the
heavens. Crosswires are strung north to south and east to west. Where these
join is a small circular iron plate with a hole in the center. The shadow cast
by this ring falls on the marble hemisphere below, indicating the sun's
longitude and latitude and the sign of the zodiac through which it is passing.
If the shadow falls on an empty space in one hemisphere, it will fall on a
solid, uncut portion in the other. The bowls have been segmented and separated
so as to allow accurate reading. The observer only has to descend the stairs to
get a close view of exactly where the shadow is lying. If the hemisphere had
been undivided, such an accurate reading would not have been possible.
Moreover, other heavenly bodies can be directly observed from the well of the
instrument. This is done by looking upward from the appropriate point on the
graduated inscription and observing the passage of the body across the
intersection of the wires.
There is an underground
passage connecting the two bowls. This is a fine example of Jai Singh's love of
things that were both practical and aesthetically pleasing. One of the most
charming and ingenious of his instruments, it is ideal for demonstrating the
apparent motion of the sun and is much used to this day in introducing
novitiate astronomers to the science.
Chakra Yantra
A graduated brass circle
that can be revolved about a diameter parallel to the earth's axis, this gives
the ascension and declination – that is, angle of an object from the equator.
It is an exact counterpart to the modern instrument known as an equatorial. On
either side of the chakra yantra lies another instrument called the kapali. It
is a miniature version of the Jai Prakash we have just seen, though here there
are no pathways cut in the bowls.
Large Ram Yantra
This and its smaller
version have the same function. What the Jai Prakash does with a sunken
hemisphere, the Ram Yantra does with an upright building. These two structures
fit together to make one whole instrument. A sector in one building corresponds
to a space in the other. There are twelve sectors in one building and eighteen
in the other, and the walls have notches for placing sighting bar. The yantra
is used to find the altitude and the azimuth of the sun
Diganta Yantra
A simple and useful
instrument, for measuring the azimuth that is, the angle of any celestial body
with the horizon. The central pin and inner wall are the same height; the outer
wall is twice as high. The inner wall can be walked along to read the
graduations of the outer.
Travel
The observatory is open
Monday through Fridays from 9AM to 4:30PM. Entry is free on Mondays and Rs.40
for Indians and Rs.200 for overseas visitors on other days. Still and moving
cameras require an extra fee. The compound is quite close to the Jaipur palace.
There is a Rs.200 guided tour that lasts from 30 to 60 minutes. An audio guide
is also available for Rs.150.
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