The 4 distinct instruments within the observatory of
Jantar Mantar in
New Delhi: the Samrat Yantra, the Jayaprakash, Rama Yantra and the
Misra Yantra. • Samrat Yantra: The Samrat Yantra, or Supreme Instrument, is a giant triangle that is basically an equal hour sundial. It is 70 feet high, 114 feet long at the base, and 10 feet thick. It has a hypotenuse that is parallel to the Earth's axis and points toward the
North Pole. On either side of the triangle is a quadrant with graduations indicating hours, minutes, and seconds. At the time of the Samrat Yantra's construction, sundials already existed, but the Samrat Yantra turned the basic hug sundial into a precision tool for measuring declination and other related coordinates of various heavenly bodies. The Vrihat Samrat Yantra can calculate the local time at an accuracy of up to two seconds and is considered the world's largest sundial. • Rama Yantra: Two large cylindrical structures with open top, used to measure the altitude of stars based on the latitude and the longitude on the Earth. • Misra Yantra: The
Misra Yantra (Literally mixed instrument) is a composition of 5 instruments designed as a tool to determine the shortest and longest days of the year. It could also be used to indicate the exact moment of noon in various cities and locations regardless of their distance from Delhi. The Misra yantra was able to indicate when it was noon in various cities all over the world and was the only structure in the observatory not invented by
Jai Singh II. • Shasthansa Yantra: Using a pinhole camera mechanism, it has been built within the towers that support the quadrant scales. It is used to measure specific measurements of the Sun such as the zenith distance, declination, and diameter of the Sun. • Kapala Yantra: Built on the same principle as the jai Prakash, the instrument is used more as a demonstration to indicate the transformation of one coordinate system to another. Not used for active celestial observation. • Rasivalya Yantra: Twelve of these structures were built, each referring to the zodiacal constellations by measuring the latitude and longitude of a celestial object at the very moment the celestial object crosses the meridian. ==Other observatories==