"The Jantar Mantar” consists of fourteen major geometric devices for measuring time, predicting eclipses, tracking stars in their orbits, ascertaining the declinations of planets, and determining the celestial altitudes and related ephemerides. Each is a fixed and 'focused' tool. The Samrat Jantar, the largest instrument, is 90 feet high, its shadow carefully plotted to tell the time of day. Its face is angled at 27 degrees, the latitude of Jaipur. The Hindu chhatri (small domed cupola) on top is used as a platform for announcing eclipses and the arrival of monsoons.
"Built of local stone and marble, each instrument carries an astronomical scale, generally marked on the marble inner lining; bronze tablets, all extraordinarily accurate, were also employed. Thoroughly restored in 1901, the Jantar Mantar was declared a national monument in 1948.
"An excursion through Jai Singh's Jantar is the singular one of walking through solid geometry and encountering a collective weapons system designed to probe the heavens."