“Jantar Mantar, is the collection of the astronomical instruments to measure the time and the position of the celestial bodies, sun, stars, moon, and planets.” The five observatories located in Delhi, Mathura, Ujjain, Varanasi, and Jaipur. The Jaipur observatory is the complete Jantar Mantar, which is still in working condition, even after 300 years of its construction. The Delhi, Mathura, Ujjain and Varanasi observatories are just the prototypes.
Maharaja Jai Singh’s Main motive behind the construction was to study astronomy through measurements. The predictions about eclipses, measurement of position and time of the celestial bodies, and measurement of local time with high precision were possible at that time because of these instruments. The instruments also used for astrology based studies. The scientific skills they used will blow your mind. I shall be taking you to a small tour of these instruments, and we will look upon the scientific skills of our ancestors.
Samrat Yantra: The sundial
The picture, shown above, is the Samrat Yantra, the sundial of the Jaipur. It shows the local time of the location. The triangular structure, which is 73 feet above the base and has a width of 9 feet, is called the gnomon. The gnomon situated between the two arcs like structures, which are at 45 feet above the surface, are called quadrants. The quadrants are marble-faced structures which have scales on it.
We know that the sun rises from the east and sets to the west. The sun rays fall on the gnomon, and its shadow’s edge on the quadrant tells us the time. When the sun rises (6 am-12 pm), the sun is in the east. Therefore, the shadow will be on the western quadrant. The shadow’s edge will fall on the scale. Similarly when the sun sets (12 pm-6 pm), the sun is in the west. Therefore, the shadow will be on the eastern quadrant. The shadow’s edge will fall on the scale. Thus, we can calculate the time.
The fact will amaze you that it can measure the time up to a precision of 20 seconds. This device shows the local time of the Jaipur. If you want to know the Indian standard time, you have to add 41 minutes to it.
Vrihat Samrat yantra: Sundial with higher precision
It is the world’s biggest and most accurate sundial of that time. The working of this sundial is similar to the Samrat yantra with a few differences. The door is in the front of the gnomon so that the shadow’s edge will fall on the gnomon’s scale, which has divisions up to 2 seconds precision. The shadow’s edge moves every 2 seconds to show the time.
Nadivalaya Yantra: Another sundial to measure the time
The problem with the Samrat yantras was they cannot show time in the night. Thus, to see the time at night and every season, the Nadivalaya Yantra was constructed. It has two circular surfaces parallel to the equator, which indicates the Northern and the Southern hemisphere. The metal pin is in the center of the circles, which is parallel to the earth’s axis. This metal pin will be the gnomon to see the time.
The clock of the southern hemisphere enables us to see the time in winter. The northern hemisphere enables us to see the time in the summers. The reason is the earth’s revolution around the sun. The earth’s southern hemisphere is in front of the sun during the winters, while the northern hemisphere is in front in the summer.
Thus, the former clock is functional from September to march, while the later clock is functional from March to September. The clock does not work on 21st March and 23rd September because the sun’s position will be between both faces, that is, on the equator.
Dhruva-Darshak Pattika: The compass
The Dhruva tara, also known as the pole star, indicates the north direction. If anyone looks straight in the sky with this yantra, then he will be able to see Dhruva star. One can find out directions; east, west, north, and south with the help of Dhruva star. Since it is in the north, then the opposite direction will be the south. The east will be on the right, and the west will be on the left. Therefore, it is also known as the compass of the astronomers.
Yantra Raj: The King of Yantras
It works in the night only. So, the astrologers and astronomers take special permission to use this yantra at night in case of any dispute. The one can know about the planets and the stars with this.
It is a bronze-circular plate, which has marks of latitude and longitudinal lines.
The hole in the center represents the Jaipur city. The Jaipur is in the center because the observations are being taken by keeping Jaipur as the reference frame. The equator line lies below the Jaipur. The one can calculate the position of various constellations at different intervals, the rotation speed of a particular planet, dates of the sun & moon eclipses, and timings of sunset & sunrise.
How does it work? The observer will keep the telescope tube on the central hole. He will have to tilt the telescope to the position of the planet and look into the sky. By this, one can find its information from the Yantra.
Jai Prakash Yantra: the complete Yantra
As you can see in the picture above, it is a bowl-shaped structure, having a diameter of 17.5 feet. The segments are divided to get access to the observers. The metal plate is in the center of the bowl, which is the sun’s position.
The bowl surface has several marks and lines. The zodiac signs, latitude & longitude, angles, and degrees, written on it, help the observer to view the azimuthal-altitude or horizontal or equatorial coordinates. These coordinates describe the location of the celestial objects. The plate’s shadow on the marble enables the observer to find the declination, position, and distance of the sun. He can use this yantra for astrological predictions as well.
The line passing in the middle, which has scales on it, is the equator line. The part above the equator is the tropic of cancer, and the portion below it is the tropic of Capricorn. It works only for one hour; after that, the shadow will shift to the missing part. Therefore, for the next hour, the other part will work. This yantra also shows the moon signs in the moonlight.
Rashivalaya Yantra: To calculate the sidereal coordinates
There are 12 sundial-like yantras, but the position is not north. Therefore, the orientation of the yantras is unusual. The purpose of this is to calculate the sidereal coordinates. The advantage of using these coordinates is that they are dependent only on the orbital movement of the earth around the sun. The astrologers use this to predict the future of the person according to his zodiac sign and birth details.
Let me clear this with an example. Suppose you are an astrologer, and you have to predict the future of a newborn baby. Then, you will first use the Jai Prakash yantra and find the zodiac sign under which the plate’s shadow is present. You will know the zodiac sign of the month. Then, you will go to the Rashivalayan yantra of the respective zodiac sign.
By the gnomon’s shadow, you will know the position of the sun in degrees when the child is born. With this information, you have to go back to the Yantra Raj to see the planet in which the child is born. With this information, you can predict the future of the child.
Rama Yantra: Altitude and Azimuth
The Rama Yantra has two parts, part A and part B, which are complementary to each other. The altitude is the height of the sun from the horizon. The azimuth is the degree of the earth rotated to its axis. Thus, it tells the altitude and azimuth. The horizontal and vertical segments have several scales for the measurement.
As the sun rises and falls, the shadow of the gnomon falls and rises accordingly around the instrument. The sun is the highest in the sky when the shadow is the lowest. The cut-outs are there for ease in taking measurements.
Kapali Yantra: The rough model of Jai Prakash Yantra
The Kapali Yantra has two parts, kapali A & kapali B. The former is to find the azimuth, altitude, meridian pass time, declination of the sun, and the local time. The later is to solve the astronomical problems graphically. It can transform one coordinate system to another coordinate system. Maharaja Jai Singh used this instrument to build the Jai Prakash Yantra. The main aim was to achieve higher accuracy in Jai Prakash.
Chakra Yantra: Global position of the sun
The Chakra Yantra tells the hemisphere in which the sun is present. It also specifies the tropical region and the shortest & the longest days & nights. The diameter of the circular ring shows the equator line of the earth. The degree scales are also present on the ring so that one can do the measurements of the position.
The observer has to insert the gnomon tube in the center hole of the ring. Then, the shadow’s edge on the ring will enable him to make observations. Therefore, one can measure the global position of the sun.
There are many more instruments such as the Misra yantra, Dakshin Bhitti yantra, Digamsha yantra, Disha yantra, Unnatamsa Yantra, Shastansh Yantra, Palbha Yantra, and other Yantras. They have their specific purpose for measurements of the positions and time of the celestial bodies, stars, planets, and constellations.
“These instruments are not in use today because of the technology era, but for that time, it was the technology. Even today, scientists and positional astronomers want to understand their scientific skills so that they can blend it with the new technology.”