Indian Astrology of Jay Singh in Jaipur
The instruments are of unique design, though the construction techniques and masonry followed Islamic practice used in mosques and castles of the period. Jai Singh’s observatories are called Jantar Mantar – literally Instrument Calculation. This Indian term for astronomical observatory derives from the Sanskrit yantra or jantar, meaning ‘instrument’; and mantra (a term familiar to the West through the Transcendental Meditation movement) which means ‘mysterious formulae for calculations.’ The observatory in Jaipur is the largest in India, and is situated next to the City Palace in the center of Jaipur.
I had an opportunity to visit the astronomical observatory at Jaipur during my recent travels through Rajasthan. And most impressive wered Jai Singh’s eclectic collection of astronomical and astrological instruments.
The huge instruments provide highly accurate measurement of time, declination of the sun, altitude and azimuth of celestial objects, the positions of the constellations for each day, eclipses and other astronomical events.
The first instrument of the movie is The Jai Prakash Yantra
The Jai Prakash Yantra (literally, Maharaja Jai’s instrument) is an intriguing instrument, designed by the Maharaja himself. It was used for verifying the readings of other instruments. It consists of two concave hemispherical marble bowls about 5.5 meters in diameter and representing the celestial hemispheres turned upside down. These two cavities are divided into six marble slabs, each engraved in minute and second graduations, marking the location of the Zodiac signs. The middle of the instrument contains a metal ring that identifies the position of the sun. The shadow of the sun falls through the metal ring, onto the graduated surface. By day, the instrument allows calculation of time; by night, observers sit inside the slabs of marble and observe celestial objects through the hole in the metal ring.
The Large and Small sun-dials
The small sundial is small only in comparison to other instruments; the sundial’s gnomon is actually a staircase of 30 steps inclined at 27 degrees (the latitude of Jaipur). It is used to calculate the declination of celestial objects. It has two quadrants on either side, which are inclined in the plane of the celestial equator (23 degrees) with divisions that provide measurement accuracy to 20 seconds. The shadow of the gnomon falls on the quadrants, allowing the reading of local time.
The large sundial is a ten-times scaled up version of the small sundial (giving a precision of 2 seconds). The base of its gnomon is 44 meters long, and rises 27 meters high, with quadrants of 15 meters radius. This is the only instrument in use today, though its use can hardly be considered scientific. Indian astrologers gather on the full moon days of June and July to study the movement an direction of the wind, which they believe will help them forecast the rains in the coming three months. For this purpose, a thin cloth flag is hoisted precisely at sunset. If the flag indicates an easterly breeze, then Rajasthan can expect good monsoons and healthy crops. If the wind is southern, Rajasthan will experience a drought, with the potential for famine. Westerly winds indicate the possibility of flooding, and northern winds indicate that crops will be good. Despite the annual regularity of this ritual, there seems to be little documentation concerning the accuracy of forecasts made in prior years.
The Zodiac Instruments (Rashi Yantra; Rashi = Zodiac) are a group of 12 instruments, each used for a specific Zodiac sign. They look like diminutive sundials. The quadrants of the sun-dials, though, are positioned on the celestial equator, while the quadrants of the Zodiac Instruments are positioned at the ecliptic at the moment of observation.