I wanted to climb the steps, but it was not allowed, and a guard stood by to ensure everyone followed the rules. Still, the idea of climbing on the giant edifices tugged at me just as it does a child who steps into an enchanting playground. And that’s what this place looked like—a playground filled with odd-shaped structures that begged to be climbed.
In reality, though, we were at Jantar Mantar—an astronomical observatory built by Maharaja Sawai Jai Singh, a soldier, scholar and ruler with a lifelong interest in math and astronomy. He founded the city of Jaipur in the 1720s and built five Jantar Mantar observatories in northern India.
Jantar Mantar means “instruments for calculation,” or “magical calculations.” The Jaipur observatory consists of 18 devices for measuring time, predicting eclipses, observing planet orbits; calculating the lunar calendar and predicting the start of the monsoon season. It’s main purpose, though, seems to have been casting horoscopes, which require a precise knowledge of the positions of the sun, moon, planets and stars at the moment of birth.
The largest instrument (with steps leading to its top) is a sundial 27 meters high, its shadow carefully plotted to tell the time of day to an accuracy of about two seconds. You can see the shadow moving at 1 millimeter per second, or roughly the width of a hand (6mm) every minute.
Influenced by the Islamic school of astronomy, Jai Singh also incorporated elements of early Greek and Persian observatories into his designs. The Jantar Mantars, however, are more complex, on a greater scale, and contain some completely unique designs and functions.
They were made almost entirely of masonry, with some engraved metal rings and plates set into masonry foundations, and they were built large because the larger the scale, the more accurate the measurements. Once finished, they could not be corrected or improved, and observations were limited to those involving the positions and motions of heavenly bodies that are visible to the naked eye.
Over the years, they’ve been restored from time to time—partly because they are tourist attractions, but also to keep them useful and scientifically authentic. Local astronomers still use them to predict the weather for farmers (although the accuracy is questionable), and students of astronomy and Vedic astrology are required to take some of their lessons at the observatories.
Because of their size and inflexibility, the Jantar Mantars were obsolete even before they were constructed and were soon replaced by smaller machined brass instruments and telescopes that proved more useful and accurate. Still, they are amazing reminders of ancient innovation and man’s quest to understand the universe.