Transcript Simon Dawes Jantar Mantar

Jantar Mantar
‘instruments and formulae’
Jaipur, India
Commissioned by Emperor Muhammad Shah to correct the
existing astronomical tables and fix planetary positions
Built by Sawai Jai Singh-II in 1728
The Jaiprakash Yantra
The Jaiprakash Yantra is in the form of two hemispherical
bowls representing the celestial spheres
Each cavity is divided into six marble slabs, divided further into
minutes and seconds and includes the signs of the zodiac
A disc suspended in the centre of each sphere
A disc suspended in the centre of each sphere, produces
a shadow on the instrument
From which you can read the position of the sun.
This instrument was the last to be built, is the most
accurate, and was used to test the other instruments.
The Ram Yantra
The Ram Yantra is two marble cylinders, with a rod mounted in
the centre.
The position of the rods the shadow marks the position of the
sun, and thus the position of celestial bodies
The twelve triangles are graduated from 90 – 45 degrees, and
the walls are graduated from 45 – 0 degrees.
The Laghu Sanrat Yantra ‘Small sun dial’
On each side of gnomon, there are two quadrants. The
left for time in the morning and right for the afternoon
The gnomon is at 27 degrees (about 14:26Hrs here)
The quadrants are graduated into hours and minutes, the
minutes are graduated into 3rds
The Nariyalya Yantra
There are two faces to this sundial, parallel to each other, one face is
used when the sun is in the northern hemisphere (21st March and
22nd September)
Rashivalaya (Star Sign) Yantra
A group of 12 instruments, with graduated quadrants on
each side. The quadrants represent the ecliptic.
When a zodiac reaches the local meridian the time on the
associated sun dial will be correct.
Yantra Raj (off screen)
Yantra Raj, only one of these is an instrument, the other
a blackboard!
Made of 7 alloys to prevent expansion and contraction.
The hole in the centre is the position of Polaris.
Using the instrument it is possible to calculate the dates of
solar and lunar eclipses, Sun rise & set, moon rise and set etc.
The Samrat Yantra ‘the King of all instruments’
(it’s behind you!)
The largest Yantra, the gnomon is 89ft high and 148ft wide,
the arches in the wall are to prevent storm damage.
Accurate to 2 seconds local time, the Samrat is still in use
today for astronomy…
And weather prediction… A flag on the top shows the wind
direction and the coming of the monsoons
Other Yantras at the site (not my photos)
Unnatasha Yantra
Chakra Yantra
Digansa Yantra
Kranti Writa Yantra
Other Yantras at the site (not my photos)
Kapali Yantra
Dhakshinodak Bhitti Yantra
Thank you