Raveesh Kumar: Jantar Mantar, Delhi

Next day, our first stop was at Jantar Mantar. Good thing about ASI monuments is that their entry is open from sunrise to sunset. So, one need not wait for some precise time for the monument to be open and make the trip plans accordingly!

Construction : The observatory was constructed by Maharaja Jai Singh II of Jaipur following the order of Delhi's Mughal emperor Muhammad Shah in 1724. It was early in the morning when we entered the place and nobody else was there. So, we could stroll around the green lawns of Jantar Mantar and take photos at will! Built primarily to estimate the times and movements of sun, moon and other planets, Jantar Mantar at Delhi is not the only such observatory in India! But it was the first one to be built. You can also find the observatories in Jaipur, Varanasi and Ujjain built by Jai Singh himself! Interestingly, there is no telescope in these observatories built by the Maharaja!

Misra Yantra, Jantar Mantar, Delhi

Yantra's : There are 13 different yantras inside the Jantar Mantar complex. To elaborate on few, Misra Yantra was designed to determine shortest and longest days of the year. It was the only instrument not invented by the Maharaja Jai Singh.
Ram Yantra was constructed to measure the horizontal and vertical angles of celestial bodies such as sun and the moon. Jai Prakash Yantra was used to determine the azimuth, altitude, declination and right ascension of celestial objects. Samrat Yantra was to measure the declination and right ascensions of celestial bodies.

spokes of Ram Yantra, Jantar Mantar, Delhi

Shasthamsa Yantra : Of the 13 instruments available in Jantar Mantar, Shasthamsa Yantra (or sextant instrument) is unique to the observatories in Delhi and Jaipur. Shasthamsa Yantra is considered to be among Jai Singh's high precision instruments. Original radius of the arc of the instrument is about 8.25 meters. This instrument is used for the measurement of the declination, zenith, distance and diameter of the sun. This Yantra consists of a large graduated 60 degree arc built in the plane of a meridian within a dark chamber. High above the arc, a pinhole is left open near the top of the chamber. The sun passes through the meridian and shines on the arc through the pinhole, from where its declination can be read.

Samrat Yantra, Jantar Mantar, Delhi

Why the name Jantar Mantar? : Jantar is modified form of Sanskrit word Yantra meaning Instrument. Mantar is modified form of Sanskrit work Mantra meaning formula. So, in totality Jantar Mantar means measuring instrument.