Jantar Mantar​—An Observatory Without Telescopes

By Awake! writer in India

VISITORS to the Jantar Mantar in New Delhi, India, may gaze at the structures there with amazement, wondering, ‘Can this really be an observatory?’ For those accustomed to modern buildings that house an array of high-tech astronomical instruments, these strange-looking masonry structures situated in a large park would hardly suggest an observatory. Yet, that is what the Jantar Mantar was when constructed in the early part of the 18th century. Remarkably, even without the benefit of telescopes and other instruments that were being developed in Europe, this observatory provided detailed and reasonably accurate information about the celestial bodies.

Jantar Mantar is the common name used for three of the five observatories built by the Rajput ruler Maharaja Sawai Jai Singh II. “Jantar” comes from the Sanskrit word “yantra,” meaning “instrument,” as  does “Mantar” from “mantra,” meaning “formula.” A colloquial practice of adding a rhyming word for emphasis has given birth to the name Jantar Mantar.

A plaque that was fixed on an instrument in the Jantar Mantar in New Delhi in 1910 gives 1710 as the year of the construction of that observatory. However, later research suggests 1724 as the date of completion. As we will see, the biographical information about Jai Singh lends support to this conclusion. But first, let us take a brief look at the instruments of this observatory, which is thought to be the oldest of its kind in the world.

Masonry Structures as Instruments

The observatory has four different instruments of masonry and stone. The most outstanding of them is the Samrat yantra, or Supreme instrument​—which is “basically an equal-hour sundial.” It was Jai Singh’s most important creation. It consists of a huge masonry triangle with a height of 70 feet [21.3 m], a base of 114 feet [34.6 m], and a width of 10 feet [3.2 m]. The 128-foot- [39 m]long hypotenuse of the triangle is parallel to the earth’s axis and points toward the North Pole. On either side of the triangle, or gnomon, is a quadrant with graduations to indicate hours, minutes, and seconds. Although simple sundials had existed for centuries, Jai Singh turned this basic instrument for measuring time into a precision tool for measuring declination and other related coordinates of the heavenly bodies.

The other three structures at the observatory are the Ram, the Jayaprakash, and the Mishra yantras. They were intricately fashioned to measure the declination, altitude, and azimuth of the sun and stars. The Mishra instrument even indicated when it was noon in various cities all over the world.

All of the aforementioned instruments except the Mishra yantra were invented by Jai Singh. They were much more complex and functional than any others existing at that time in India and led to the development of accurate almanacs and astronomical tables. In design they were graceful and pleasing to the eye and gave valuable information until the telescope and other inventions made them obsolete. Why, though, did this brilliant and scholarly man not incorporate into his astronomical research some of the devices available in Europe, including an optical telescope? The answer is to be found in the background of the maharaja and in the history of the times.

“Devoted to the Study of Mathematical Science”

Jai Singh was born in 1688 in the Indian state of Rajasthan. His father, a maharaja in Amber, the capital of the Kachavaha clan of Rajputs, was under the authority of the Mogul powers in Delhi. The young prince was educated in such languages as Hindi, Sanskrit,  Persian, and Arabic. He also received education in mathematics, astronomy, and the martial arts. But one subject was closest to the prince’s heart. A text of his times states: “Sawai Jai Singh from the first dawning of reason in his mind, and during its progress toward maturity, was entirely devoted to the study of mathematical science (astronomy).”

In 1700, at the age of 11, Jai Singh ascended the throne of Amber, following the death of his father. Soon the young king was called by the Mogul emperor to his court in south India, where Jai Singh met Jagannātha, a man well versed in mathematics and astronomy. This man later became the king’s principal assistant. The young maharaja’s political fortunes fluctuated until 1719, when the reign of Muḥammad Shāh began. Jai Singh was then called to the capital, Delhi, for a meeting with the new Mogul ruler. At this meeting, held in November 1720, Jai Singh apparently proposed the building of an observatory, which probably became a reality in 1724.

What motivated the maharaja to build an observatory? Jai Singh realized that the almanacs and astronomical charts in India were sadly inaccurate and that little progress was being made in the field of astronomy. So he decided to make new charts that would correspond to the actual visible heavenly bodies. He also had a desire to make instruments for astronomical observations available to every person devoted to the study of astronomy. Jai Singh thus acquired a vast library of books from France, England, Portugal, and Germany. In his court, he welcomed scholars from Hindu, Islamic, and European schools of astronomy. He even sent the first fact-finding mission from the East to Europe to collect information on astronomy, and he commissioned them to bring back books and instruments.

East and West Could Not Meet

Why did Jai Singh build masonry structures, even though the telescope, the micrometer, and the vernier were in use in Europe? And why did he seem unfamiliar with the heliocentric discoveries of Copernicus and Galileo?

Poor communication between East and West must carry some of the blame. But that was not the only drawback. The religious climate of the time was also responsible. Brahman scholars refused to travel to Europe because crossing the ocean could mean losing their caste. The European assistants who helped Jai Singh gather information were mainly Jesuit scholars. According to V. N. Sharma, who wrote a biography of Jai Singh, the Jesuits along with Catholic laymen were prohibited under threat of the Inquisition to accept the view held by Galileo and other scientists that the earth revolved around the sun. To the church this was heresy and atheism. It is not surprising then that the emissaries sent to Europe by Jai Singh did not include in their shopping lists works of Copernicus and Galileo or the new instruments that were being used to support the heliocentric theories.

An Ongoing Quest

Jai Singh lived in an age marred by religious intolerance and bigotry. Despite his brilliant and masterful work in updating knowledge of the heavens, little further progress was made in this field in India for decades. Yet, the Jantar Mantar observatory is a testimony to the efforts of a man who had a thirst for knowledge.

For centuries before Jai Singh developed an interest in the movement of the celestial bodies, other thinking humans were looking at the sky, trying to understand the wonders of the universe. No doubt mankind will continue to ‘raise their eyes high up’ to the heavens in a quest to increase their knowledge of the works of God’s hands.​—Isaiah 40:26; Psalm 19:1.

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Samrat yantra was a precise sundial. The shadow of the large triangle was cast onto the curved quadrants (see highlighted white circle) where graduations were marked on them

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Jayaprakash yantra consists of hollowed-out hemispheres with markings on the concave surface. Crosswires were stretched between points on the rim

From the inside of the Ram yantra, an observer could align the position of a star with various markings or a window’s edge

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Mishra yantra indicated when it was noon in various cities

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Line-of-sight observation, the earliest form of astronomy, was made very precise by Jai Singh

To locate a star, you need to know its altitude (how high it is in the sky) and its azimuth (how far east it is from true north)

At the Samrat yantra, it took two people to pinpoint a star and record its position

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Bottom: Reproduced from the book SAWAI JAI SINGH AND HIS ASTRONOMY, published by Motilal Banarsidass Publishers (P) Ltd., Jawahar Nagar Delhi, India

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INDIA

New Delhi

Mathura

Jaipur

Varanasi

Ujjain

Jai Singh built five observatories in India, including one in New Delhi

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Portrait: Courtesy Roop Kishore Goyal